From 83604a497a3b7ac03b0b9bb28675d4c633b3a210 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Marcin=20Wcis=C5=82o?= Date: Thu, 16 Jul 2026 20:04:48 +0200 Subject: [PATCH 01/18] neigh: introduce neigh_confirm() helper function MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit jira VULN-162723 cve-pre CVE-2025-40158 commit-author Yajun Deng commit 1e84dc6b7bbfc4d1dd846decece4611b7e035772 Add neigh_confirm() for the confirmed member in struct neighbour, it can be called as an independent unit by other functions. Signed-off-by: Yajun Deng Reviewed-by: Eric Dumazet Signed-off-by: David S. Miller (cherry picked from commit 1e84dc6b7bbfc4d1dd846decece4611b7e035772) Signed-off-by: Marcin Wcisło --- include/net/arp.h | 8 +------- include/net/ndisc.h | 16 ++-------------- include/net/neighbour.h | 11 +++++++++++ include/net/sock.h | 5 +---- 4 files changed, 15 insertions(+), 25 deletions(-) diff --git a/include/net/arp.h b/include/net/arp.h index 4a23a97195f33..d7ef4ec71dfeb 100644 --- a/include/net/arp.h +++ b/include/net/arp.h @@ -53,13 +53,7 @@ static inline void __ipv4_confirm_neigh(struct net_device *dev, u32 key) rcu_read_lock_bh(); n = __ipv4_neigh_lookup_noref(dev, key); - if (n) { - unsigned long now = jiffies; - - /* avoid dirtying neighbour */ - if (READ_ONCE(n->confirmed) != now) - WRITE_ONCE(n->confirmed, now); - } + neigh_confirm(n); rcu_read_unlock_bh(); } diff --git a/include/net/ndisc.h b/include/net/ndisc.h index 19efe396816bf..6503545a33dd9 100644 --- a/include/net/ndisc.h +++ b/include/net/ndisc.h @@ -411,13 +411,7 @@ static inline void __ipv6_confirm_neigh(struct net_device *dev, rcu_read_lock_bh(); n = __ipv6_neigh_lookup_noref(dev, pkey); - if (n) { - unsigned long now = jiffies; - - /* avoid dirtying neighbour */ - if (READ_ONCE(n->confirmed) != now) - WRITE_ONCE(n->confirmed, now); - } + neigh_confirm(n); rcu_read_unlock_bh(); } @@ -428,13 +422,7 @@ static inline void __ipv6_confirm_neigh_stub(struct net_device *dev, rcu_read_lock_bh(); n = __ipv6_neigh_lookup_noref_stub(dev, pkey); - if (n) { - unsigned long now = jiffies; - - /* avoid dirtying neighbour */ - if (READ_ONCE(n->confirmed) != now) - WRITE_ONCE(n->confirmed, now); - } + neigh_confirm(n); rcu_read_unlock_bh(); } diff --git a/include/net/neighbour.h b/include/net/neighbour.h index b14ea30e40117..fbee2336f8397 100644 --- a/include/net/neighbour.h +++ b/include/net/neighbour.h @@ -330,6 +330,17 @@ static inline struct neighbour *__neigh_lookup_noref(struct neigh_table *tbl, return ___neigh_lookup_noref(tbl, tbl->key_eq, tbl->hash, pkey, dev); } +static inline void neigh_confirm(struct neighbour *n) +{ + if (n) { + unsigned long now = jiffies; + + /* avoid dirtying neighbour */ + if (READ_ONCE(n->confirmed) != now) + WRITE_ONCE(n->confirmed, now); + } +} + void neigh_table_init(int index, struct neigh_table *tbl); int neigh_table_clear(int index, struct neigh_table *tbl); struct neighbour *neigh_lookup(struct neigh_table *tbl, const void *pkey, diff --git a/include/net/sock.h b/include/net/sock.h index 3d0881b6f8aae..675220277c47d 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -2236,13 +2236,10 @@ static inline void sock_confirm_neigh(struct sk_buff *skb, struct neighbour *n) { if (skb_get_dst_pending_confirm(skb)) { struct sock *sk = skb->sk; - unsigned long now = jiffies; - /* avoid dirtying neighbour */ - if (READ_ONCE(n->confirmed) != now) - WRITE_ONCE(n->confirmed, now); if (sk && READ_ONCE(sk->sk_dst_pending_confirm)) WRITE_ONCE(sk->sk_dst_pending_confirm, 0); + neigh_confirm(n); } } From d50f0934306370fb173388c51d09e91da88d57f7 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Marcin=20Wcis=C5=82o?= Date: Thu, 16 Jul 2026 20:04:49 +0200 Subject: [PATCH 02/18] ipv6: remove one read_lock()/read_unlock() pair in rt6_check_neigh() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit jira VULN-162723 cve-pre CVE-2025-40158 commit-author Eric Dumazet commit c486640aa710ddd06c13a7f7162126e1552e8842 rt6_check_neigh() uses read_lock() to protect n->nud_state reading. This seems overkill and causes false sharing. Signed-off-by: Eric Dumazet Reviewed-by: David Ahern Reviewed-by: Martin KaFai Lau Signed-off-by: Jakub Kicinski (cherry picked from commit c486640aa710ddd06c13a7f7162126e1552e8842) Signed-off-by: Marcin Wcisło --- net/ipv6/route.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/net/ipv6/route.c b/net/ipv6/route.c index cbd70b02f1fc6..db5a3c6645471 100644 --- a/net/ipv6/route.c +++ b/net/ipv6/route.c @@ -696,16 +696,16 @@ static enum rt6_nud_state rt6_check_neigh(const struct fib6_nh *fib6_nh) neigh = __ipv6_neigh_lookup_noref(fib6_nh->fib_nh_dev, &fib6_nh->fib_nh_gw6); if (neigh) { - read_lock(&neigh->lock); - if (neigh->nud_state & NUD_VALID) + u8 nud_state = READ_ONCE(neigh->nud_state); + + if (nud_state & NUD_VALID) ret = RT6_NUD_SUCCEED; #ifdef CONFIG_IPV6_ROUTER_PREF - else if (!(neigh->nud_state & NUD_FAILED)) + else if (!(nud_state & NUD_FAILED)) ret = RT6_NUD_SUCCEED; else ret = RT6_NUD_FAIL_PROBE; #endif - read_unlock(&neigh->lock); } else { ret = IS_ENABLED(CONFIG_IPV6_ROUTER_PREF) ? RT6_NUD_SUCCEED : RT6_NUD_FAIL_DO_RR; From 54cf43d3f99ea5ae02c53b3f37f60ae27487c80c Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Marcin=20Wcis=C5=82o?= Date: Thu, 16 Jul 2026 20:04:49 +0200 Subject: [PATCH 03/18] ipv6: flowlabel: do not disable BH where not needed MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit jira VULN-162723 cve-pre CVE-2025-40158 commit-author Eric Dumazet commit 4c5c496a942fa3d2197f5be22762695170c95863 struct ip6_flowlabel are rcu managed, and call_rcu() is used to delay fl_free_rcu() after RCU grace period. There is no point disabling BH for pure RCU lookups. Signed-off-by: Eric Dumazet Signed-off-by: Jakub Kicinski (cherry picked from commit 4c5c496a942fa3d2197f5be22762695170c95863) Signed-off-by: Marcin Wcisło --- net/ipv6/ip6_flowlabel.c | 51 +++++++++++++++++++++------------------- 1 file changed, 27 insertions(+), 24 deletions(-) diff --git a/net/ipv6/ip6_flowlabel.c b/net/ipv6/ip6_flowlabel.c index 18481eb76a0a4..b3ca4beb4405a 100644 --- a/net/ipv6/ip6_flowlabel.c +++ b/net/ipv6/ip6_flowlabel.c @@ -58,18 +58,18 @@ DEFINE_STATIC_KEY_DEFERRED_FALSE(ipv6_flowlabel_exclusive, HZ); EXPORT_SYMBOL(ipv6_flowlabel_exclusive); #define for_each_fl_rcu(hash, fl) \ - for (fl = rcu_dereference_bh(fl_ht[(hash)]); \ + for (fl = rcu_dereference(fl_ht[(hash)]); \ fl != NULL; \ - fl = rcu_dereference_bh(fl->next)) + fl = rcu_dereference(fl->next)) #define for_each_fl_continue_rcu(fl) \ - for (fl = rcu_dereference_bh(fl->next); \ + for (fl = rcu_dereference(fl->next); \ fl != NULL; \ - fl = rcu_dereference_bh(fl->next)) + fl = rcu_dereference(fl->next)) #define for_each_sk_fl_rcu(np, sfl) \ - for (sfl = rcu_dereference_bh(np->ipv6_fl_list); \ + for (sfl = rcu_dereference(np->ipv6_fl_list); \ sfl != NULL; \ - sfl = rcu_dereference_bh(sfl->next)) + sfl = rcu_dereference(sfl->next)) static inline struct ip6_flowlabel *__fl_lookup(struct net *net, __be32 label) { @@ -86,11 +86,11 @@ static struct ip6_flowlabel *fl_lookup(struct net *net, __be32 label) { struct ip6_flowlabel *fl; - rcu_read_lock_bh(); + rcu_read_lock(); fl = __fl_lookup(net, label); if (fl && !atomic_inc_not_zero(&fl->users)) fl = NULL; - rcu_read_unlock_bh(); + rcu_read_unlock(); return fl; } @@ -217,6 +217,7 @@ static struct ip6_flowlabel *fl_intern(struct net *net, fl->label = label & IPV6_FLOWLABEL_MASK; + rcu_read_lock(); spin_lock_bh(&ip6_fl_lock); if (label == 0) { for (;;) { @@ -240,6 +241,7 @@ static struct ip6_flowlabel *fl_intern(struct net *net, if (lfl) { atomic_inc(&lfl->users); spin_unlock_bh(&ip6_fl_lock); + rcu_read_unlock(); return lfl; } } @@ -249,6 +251,7 @@ static struct ip6_flowlabel *fl_intern(struct net *net, rcu_assign_pointer(fl_ht[FL_HASH(fl->label)], fl); atomic_inc(&fl_size); spin_unlock_bh(&ip6_fl_lock); + rcu_read_unlock(); return NULL; } @@ -263,17 +266,17 @@ struct ip6_flowlabel *__fl6_sock_lookup(struct sock *sk, __be32 label) label &= IPV6_FLOWLABEL_MASK; - rcu_read_lock_bh(); + rcu_read_lock(); for_each_sk_fl_rcu(np, sfl) { struct ip6_flowlabel *fl = sfl->fl; if (fl->label == label && atomic_inc_not_zero(&fl->users)) { fl->lastuse = jiffies; - rcu_read_unlock_bh(); + rcu_read_unlock(); return fl; } } - rcu_read_unlock_bh(); + rcu_read_unlock(); return NULL; } EXPORT_SYMBOL_GPL(__fl6_sock_lookup); @@ -475,10 +478,10 @@ static int mem_check(struct sock *sk) if (room > FL_MAX_SIZE - FL_MAX_PER_SOCK) return 0; - rcu_read_lock_bh(); + rcu_read_lock(); for_each_sk_fl_rcu(np, sfl) count++; - rcu_read_unlock_bh(); + rcu_read_unlock(); if (room <= 0 || ((count >= FL_MAX_PER_SOCK || @@ -515,7 +518,7 @@ int ipv6_flowlabel_opt_get(struct sock *sk, struct in6_flowlabel_req *freq, return 0; } - rcu_read_lock_bh(); + rcu_read_lock(); for_each_sk_fl_rcu(np, sfl) { if (sfl->fl->label == (np->flow_label & IPV6_FLOWLABEL_MASK)) { @@ -527,11 +530,11 @@ int ipv6_flowlabel_opt_get(struct sock *sk, struct in6_flowlabel_req *freq, freq->flr_linger = sfl->fl->linger / HZ; spin_unlock_bh(&ip6_fl_lock); - rcu_read_unlock_bh(); + rcu_read_unlock(); return 0; } } - rcu_read_unlock_bh(); + rcu_read_unlock(); return -ENOENT; } @@ -581,16 +584,16 @@ static int ipv6_flowlabel_renew(struct sock *sk, struct in6_flowlabel_req *freq) struct ipv6_fl_socklist *sfl; int err; - rcu_read_lock_bh(); + rcu_read_lock(); for_each_sk_fl_rcu(np, sfl) { if (sfl->fl->label == freq->flr_label) { err = fl6_renew(sfl->fl, freq->flr_linger, freq->flr_expires); - rcu_read_unlock_bh(); + rcu_read_unlock(); return err; } } - rcu_read_unlock_bh(); + rcu_read_unlock(); if (freq->flr_share == IPV6_FL_S_NONE && ns_capable(net->user_ns, CAP_NET_ADMIN)) { @@ -641,11 +644,11 @@ static int ipv6_flowlabel_get(struct sock *sk, struct in6_flowlabel_req *freq, if (freq->flr_label) { err = -EEXIST; - rcu_read_lock_bh(); + rcu_read_lock(); for_each_sk_fl_rcu(np, sfl) { if (sfl->fl->label == freq->flr_label) { if (freq->flr_flags & IPV6_FL_F_EXCL) { - rcu_read_unlock_bh(); + rcu_read_unlock(); goto done; } fl1 = sfl->fl; @@ -654,7 +657,7 @@ static int ipv6_flowlabel_get(struct sock *sk, struct in6_flowlabel_req *freq, break; } } - rcu_read_unlock_bh(); + rcu_read_unlock(); if (!fl1) fl1 = fl_lookup(net, freq->flr_label); @@ -809,7 +812,7 @@ static void *ip6fl_seq_start(struct seq_file *seq, loff_t *pos) state->pid_ns = proc_pid_ns(file_inode(seq->file)->i_sb); - rcu_read_lock_bh(); + rcu_read_lock(); return *pos ? ip6fl_get_idx(seq, *pos - 1) : SEQ_START_TOKEN; } @@ -828,7 +831,7 @@ static void *ip6fl_seq_next(struct seq_file *seq, void *v, loff_t *pos) static void ip6fl_seq_stop(struct seq_file *seq, void *v) __releases(RCU) { - rcu_read_unlock_bh(); + rcu_read_unlock(); } static int ip6fl_seq_show(struct seq_file *seq, void *v) From fe34ee649486a4522586b7a608a6c2c001405b5d Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Marcin=20Wcis=C5=82o?= Date: Thu, 16 Jul 2026 20:04:50 +0200 Subject: [PATCH 04/18] neighbour: switch to standard rcu, instead of rcu_bh MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit jira VULN-162723 cve-pre CVE-2025-40158 commit-author Eric Dumazet commit 09eed1192cec1755967f2af8394207acdde579a1 upstream-diff Used CentOS 9 backport 8b5b9707c3f82d029fbcad0997be1905bdd6945e for a clean pick rcu_bh is no longer a win, especially for objects freed with standard call_rcu(). Switch neighbour code to no longer disable BH when not necessary. Signed-off-by: Eric Dumazet Signed-off-by: Jakub Kicinski (cherry picked from commit 8b5b9707c3f82d029fbcad0997be1905bdd6945e) Signed-off-by: Marcin Wcisło --- include/net/arp.h | 8 ++--- include/net/ndisc.h | 12 ++++---- include/net/neighbour.h | 6 ++-- include/net/nexthop.h | 6 ++-- net/core/filter.c | 16 ++++++---- net/core/neighbour.c | 64 ++++++++++++++++++++-------------------- net/ipv4/fib_semantics.c | 4 +-- net/ipv4/ip_output.c | 6 ++-- net/ipv4/nexthop.c | 8 ++--- net/ipv4/route.c | 4 +-- net/ipv6/addrconf.c | 14 ++++----- net/ipv6/ip6_output.c | 10 +++---- net/ipv6/route.c | 12 ++++---- 13 files changed, 87 insertions(+), 83 deletions(-) diff --git a/include/net/arp.h b/include/net/arp.h index d7ef4ec71dfeb..e8747e0713c79 100644 --- a/include/net/arp.h +++ b/include/net/arp.h @@ -38,11 +38,11 @@ static inline struct neighbour *__ipv4_neigh_lookup(struct net_device *dev, u32 { struct neighbour *n; - rcu_read_lock_bh(); + rcu_read_lock(); n = __ipv4_neigh_lookup_noref(dev, key); if (n && !refcount_inc_not_zero(&n->refcnt)) n = NULL; - rcu_read_unlock_bh(); + rcu_read_unlock(); return n; } @@ -51,10 +51,10 @@ static inline void __ipv4_confirm_neigh(struct net_device *dev, u32 key) { struct neighbour *n; - rcu_read_lock_bh(); + rcu_read_lock(); n = __ipv4_neigh_lookup_noref(dev, key); neigh_confirm(n); - rcu_read_unlock_bh(); + rcu_read_unlock(); } void arp_init(void); diff --git a/include/net/ndisc.h b/include/net/ndisc.h index 6503545a33dd9..1da33f4cf3a5b 100644 --- a/include/net/ndisc.h +++ b/include/net/ndisc.h @@ -395,11 +395,11 @@ static inline struct neighbour *__ipv6_neigh_lookup(struct net_device *dev, cons { struct neighbour *n; - rcu_read_lock_bh(); + rcu_read_lock(); n = __ipv6_neigh_lookup_noref(dev, pkey); if (n && !refcount_inc_not_zero(&n->refcnt)) n = NULL; - rcu_read_unlock_bh(); + rcu_read_unlock(); return n; } @@ -409,10 +409,10 @@ static inline void __ipv6_confirm_neigh(struct net_device *dev, { struct neighbour *n; - rcu_read_lock_bh(); + rcu_read_lock(); n = __ipv6_neigh_lookup_noref(dev, pkey); neigh_confirm(n); - rcu_read_unlock_bh(); + rcu_read_unlock(); } static inline void __ipv6_confirm_neigh_stub(struct net_device *dev, @@ -420,10 +420,10 @@ static inline void __ipv6_confirm_neigh_stub(struct net_device *dev, { struct neighbour *n; - rcu_read_lock_bh(); + rcu_read_lock(); n = __ipv6_neigh_lookup_noref_stub(dev, pkey); neigh_confirm(n); - rcu_read_unlock_bh(); + rcu_read_unlock(); } /* uses ipv6_stub and is meant for use outside of IPv6 core */ diff --git a/include/net/neighbour.h b/include/net/neighbour.h index fbee2336f8397..96505385039c4 100644 --- a/include/net/neighbour.h +++ b/include/net/neighbour.h @@ -308,14 +308,14 @@ static inline struct neighbour *___neigh_lookup_noref( const void *pkey, struct net_device *dev) { - struct neigh_hash_table *nht = rcu_dereference_bh(tbl->nht); + struct neigh_hash_table *nht = rcu_dereference(tbl->nht); struct neighbour *n; u32 hash_val; hash_val = hash(pkey, dev, nht->hash_rnd) >> (32 - nht->hash_shift); - for (n = rcu_dereference_bh(nht->hash_buckets[hash_val]); + for (n = rcu_dereference(nht->hash_buckets[hash_val]); n != NULL; - n = rcu_dereference_bh(n->next)) { + n = rcu_dereference(n->next)) { if (n->dev == dev && key_eq(n, pkey)) return n; } diff --git a/include/net/nexthop.h b/include/net/nexthop.h index 09e1c34fb0570..f3b0706ee8c72 100644 --- a/include/net/nexthop.h +++ b/include/net/nexthop.h @@ -533,7 +533,7 @@ static inline struct fib6_nh *nexthop_fib6_nh(struct nexthop *nh) } /* Variant of nexthop_fib6_nh(). - * Caller should either hold rcu_read_lock_bh(), or RTNL. + * Caller should either hold rcu_read_lock(), or RTNL. */ static inline struct fib6_nh *nexthop_fib6_nh_bh(struct nexthop *nh) { @@ -542,13 +542,13 @@ static inline struct fib6_nh *nexthop_fib6_nh_bh(struct nexthop *nh) if (nh->is_group) { struct nh_group *nh_grp; - nh_grp = rcu_dereference_bh_rtnl(nh->nh_grp); + nh_grp = rcu_dereference_rtnl(nh->nh_grp); nh = nexthop_mpath_select(nh_grp, 0); if (!nh) return NULL; } - nhi = rcu_dereference_bh_rtnl(nh->nh_info); + nhi = rcu_dereference_rtnl(nh->nh_info); if (nhi->family == AF_INET6) return &nhi->fib6_nh; diff --git a/net/core/filter.c b/net/core/filter.c index 2d6f978ba9c96..92434a04ec805 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -2206,7 +2206,7 @@ static int bpf_out_neigh_v6(struct net *net, struct sk_buff *skb, return -ENOMEM; } - rcu_read_lock_bh(); + rcu_read_lock(); if (!nh) { dst = skb_dst(skb); nexthop = rt6_nexthop(container_of(dst, struct rt6_info, dst), @@ -2219,10 +2219,12 @@ static int bpf_out_neigh_v6(struct net *net, struct sk_buff *skb, int ret; sock_confirm_neigh(skb, neigh); + local_bh_disable(); dev_xmit_recursion_inc(); ret = neigh_output(neigh, skb, false); dev_xmit_recursion_dec(); - rcu_read_unlock_bh(); + local_bh_enable(); + rcu_read_unlock(); return ret; } rcu_read_unlock_bh(); @@ -2304,7 +2306,7 @@ static int bpf_out_neigh_v4(struct net *net, struct sk_buff *skb, return -ENOMEM; } - rcu_read_lock_bh(); + rcu_read_lock(); if (!nh) { struct dst_entry *dst = skb_dst(skb); struct rtable *rt = container_of(dst, struct rtable, dst); @@ -2316,7 +2318,7 @@ static int bpf_out_neigh_v4(struct net *net, struct sk_buff *skb, } else if (nh->nh_family == AF_INET) { neigh = ip_neigh_gw4(dev, nh->ipv4_nh); } else { - rcu_read_unlock_bh(); + rcu_read_unlock(); goto out_drop; } @@ -2324,13 +2326,15 @@ static int bpf_out_neigh_v4(struct net *net, struct sk_buff *skb, int ret; sock_confirm_neigh(skb, neigh); + local_bh_disable(); dev_xmit_recursion_inc(); ret = neigh_output(neigh, skb, is_v6gw); dev_xmit_recursion_dec(); - rcu_read_unlock_bh(); + local_bh_enable(); + rcu_read_unlock(); return ret; } - rcu_read_unlock_bh(); + rcu_read_unlock(); out_drop: kfree_skb(skb); return -ENETDOWN; diff --git a/net/core/neighbour.c b/net/core/neighbour.c index fe40ad5454509..be00227e2aec6 100644 --- a/net/core/neighbour.c +++ b/net/core/neighbour.c @@ -571,7 +571,7 @@ struct neighbour *neigh_lookup(struct neigh_table *tbl, const void *pkey, NEIGH_CACHE_STAT_INC(tbl, lookups); - rcu_read_lock_bh(); + rcu_read_lock(); n = __neigh_lookup_noref(tbl, pkey, dev); if (n) { if (!refcount_inc_not_zero(&n->refcnt)) @@ -579,7 +579,7 @@ struct neighbour *neigh_lookup(struct neigh_table *tbl, const void *pkey, NEIGH_CACHE_STAT_INC(tbl, hits); } - rcu_read_unlock_bh(); + rcu_read_unlock(); return n; } EXPORT_SYMBOL(neigh_lookup); @@ -2164,11 +2164,11 @@ static int neightbl_fill_info(struct sk_buff *skb, struct neigh_table *tbl, .ndtc_proxy_qlen = tbl->proxy_queue.qlen, }; - rcu_read_lock_bh(); - nht = rcu_dereference_bh(tbl->nht); + rcu_read_lock(); + nht = rcu_dereference(tbl->nht); ndc.ndtc_hash_rnd = nht->hash_rnd[0]; ndc.ndtc_hash_mask = ((1 << nht->hash_shift) - 1); - rcu_read_unlock_bh(); + rcu_read_unlock(); if (nla_put(skb, NDTA_CONFIG, sizeof(ndc), &ndc)) goto nla_put_failure; @@ -2678,15 +2678,15 @@ static int neigh_dump_table(struct neigh_table *tbl, struct sk_buff *skb, if (filter->dev_idx || filter->master_idx) flags |= NLM_F_DUMP_FILTERED; - rcu_read_lock_bh(); - nht = rcu_dereference_bh(tbl->nht); + rcu_read_lock(); + nht = rcu_dereference(tbl->nht); for (h = s_h; h < (1 << nht->hash_shift); h++) { if (h > s_h) s_idx = 0; - for (n = rcu_dereference_bh(nht->hash_buckets[h]), idx = 0; + for (n = rcu_dereference(nht->hash_buckets[h]), idx = 0; n != NULL; - n = rcu_dereference_bh(n->next)) { + n = rcu_dereference(n->next)) { if (idx < s_idx || !net_eq(dev_net(n->dev), net)) goto next; if (neigh_ifindex_filtered(n->dev, filter->dev_idx) || @@ -2705,7 +2705,7 @@ static int neigh_dump_table(struct neigh_table *tbl, struct sk_buff *skb, } rc = skb->len; out: - rcu_read_unlock_bh(); + rcu_read_unlock(); cb->args[1] = h; cb->args[2] = idx; return rc; @@ -3050,20 +3050,20 @@ void neigh_for_each(struct neigh_table *tbl, void (*cb)(struct neighbour *, void int chain; struct neigh_hash_table *nht; - rcu_read_lock_bh(); - nht = rcu_dereference_bh(tbl->nht); + rcu_read_lock(); + nht = rcu_dereference(tbl->nht); - read_lock(&tbl->lock); /* avoid resizes */ + read_lock_bh(&tbl->lock); /* avoid resizes */ for (chain = 0; chain < (1 << nht->hash_shift); chain++) { struct neighbour *n; - for (n = rcu_dereference_bh(nht->hash_buckets[chain]); + for (n = rcu_dereference(nht->hash_buckets[chain]); n != NULL; - n = rcu_dereference_bh(n->next)) + n = rcu_dereference(n->next)) cb(n, cookie); } - read_unlock(&tbl->lock); - rcu_read_unlock_bh(); + read_unlock_bh(&tbl->lock); + rcu_read_unlock(); } EXPORT_SYMBOL(neigh_for_each); @@ -3113,7 +3113,7 @@ int neigh_xmit(int index, struct net_device *dev, tbl = neigh_tables[index]; if (!tbl) goto out; - rcu_read_lock_bh(); + rcu_read_lock(); if (index == NEIGH_ARP_TABLE) { u32 key = *((u32 *)addr); @@ -3125,11 +3125,11 @@ int neigh_xmit(int index, struct net_device *dev, neigh = __neigh_create(tbl, addr, dev, false); err = PTR_ERR(neigh); if (IS_ERR(neigh)) { - rcu_read_unlock_bh(); + rcu_read_unlock(); goto out_kfree_skb; } err = neigh->output(neigh, skb); - rcu_read_unlock_bh(); + rcu_read_unlock(); } else if (index == NEIGH_LINK_TABLE) { err = dev_hard_header(skb, dev, ntohs(skb->protocol), @@ -3158,7 +3158,7 @@ static struct neighbour *neigh_get_first(struct seq_file *seq) state->flags &= ~NEIGH_SEQ_IS_PNEIGH; for (bucket = 0; bucket < (1 << nht->hash_shift); bucket++) { - n = rcu_dereference_bh(nht->hash_buckets[bucket]); + n = rcu_dereference(nht->hash_buckets[bucket]); while (n) { if (!net_eq(dev_net(n->dev), net)) @@ -3176,7 +3176,7 @@ static struct neighbour *neigh_get_first(struct seq_file *seq) if (READ_ONCE(n->nud_state) & ~NUD_NOARP) break; next: - n = rcu_dereference_bh(n->next); + n = rcu_dereference(n->next); } if (n) @@ -3200,7 +3200,7 @@ static struct neighbour *neigh_get_next(struct seq_file *seq, if (v) return n; } - n = rcu_dereference_bh(n->next); + n = rcu_dereference(n->next); while (1) { while (n) { @@ -3218,7 +3218,7 @@ static struct neighbour *neigh_get_next(struct seq_file *seq, if (READ_ONCE(n->nud_state) & ~NUD_NOARP) break; next: - n = rcu_dereference_bh(n->next); + n = rcu_dereference(n->next); } if (n) @@ -3227,7 +3227,7 @@ static struct neighbour *neigh_get_next(struct seq_file *seq, if (++state->bucket >= (1 << nht->hash_shift)) break; - n = rcu_dereference_bh(nht->hash_buckets[state->bucket]); + n = rcu_dereference(nht->hash_buckets[state->bucket]); } if (n && pos) @@ -3329,7 +3329,7 @@ static void *neigh_get_idx_any(struct seq_file *seq, loff_t *pos) void *neigh_seq_start(struct seq_file *seq, loff_t *pos, struct neigh_table *tbl, unsigned int neigh_seq_flags) __acquires(tbl->lock) - __acquires(rcu_bh) + __acquires(rcu) { struct neigh_seq_state *state = seq->private; @@ -3337,9 +3337,9 @@ void *neigh_seq_start(struct seq_file *seq, loff_t *pos, struct neigh_table *tbl state->bucket = 0; state->flags = (neigh_seq_flags & ~NEIGH_SEQ_IS_PNEIGH); - rcu_read_lock_bh(); - state->nht = rcu_dereference_bh(tbl->nht); - read_lock(&tbl->lock); + rcu_read_lock(); + state->nht = rcu_dereference(tbl->nht); + read_lock_bh(&tbl->lock); return *pos ? neigh_get_idx_any(seq, pos) : SEQ_START_TOKEN; } @@ -3374,13 +3374,13 @@ EXPORT_SYMBOL(neigh_seq_next); void neigh_seq_stop(struct seq_file *seq, void *v) __releases(tbl->lock) - __releases(rcu_bh) + __releases(rcu) { struct neigh_seq_state *state = seq->private; struct neigh_table *tbl = state->tbl; - read_unlock(&tbl->lock); - rcu_read_unlock_bh(); + read_unlock_bh(&tbl->lock); + rcu_read_unlock(); } EXPORT_SYMBOL(neigh_seq_stop); diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c index c5cce187c4b4a..6e7122d54abf9 100644 --- a/net/ipv4/fib_semantics.c +++ b/net/ipv4/fib_semantics.c @@ -2221,7 +2221,7 @@ static bool fib_good_nh(const struct fib_nh *nh) if (nh->fib_nh_scope == RT_SCOPE_LINK) { struct neighbour *n; - rcu_read_lock_bh(); + rcu_read_lock(); if (likely(nh->fib_nh_gw_family == AF_INET)) n = __ipv4_neigh_lookup_noref(nh->fib_nh_dev, @@ -2234,7 +2234,7 @@ static bool fib_good_nh(const struct fib_nh *nh) if (n) state = READ_ONCE(n->nud_state); - rcu_read_unlock_bh(); + rcu_read_unlock(); } return !!(state & NUD_VALID); diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c index d61499a11d34e..4d5c3d86d25c9 100644 --- a/net/ipv4/ip_output.c +++ b/net/ipv4/ip_output.c @@ -225,7 +225,7 @@ static int ip_finish_output2(struct net *net, struct sock *sk, struct sk_buff *s return res; } - rcu_read_lock_bh(); + rcu_read_lock(); neigh = ip_neigh_for_gw(rt, skb, &is_v6gw); if (!IS_ERR(neigh)) { int res; @@ -233,10 +233,10 @@ static int ip_finish_output2(struct net *net, struct sock *sk, struct sk_buff *s sock_confirm_neigh(skb, neigh); /* if crossing protocols, can not use the cached header */ res = neigh_output(neigh, skb, is_v6gw); - rcu_read_unlock_bh(); + rcu_read_unlock(); return res; } - rcu_read_unlock_bh(); + rcu_read_unlock(); net_dbg_ratelimited("%s: No header cache and no neighbour!\n", __func__); diff --git a/net/ipv4/nexthop.c b/net/ipv4/nexthop.c index 535433ef02b17..951c1bc5aa595 100644 --- a/net/ipv4/nexthop.c +++ b/net/ipv4/nexthop.c @@ -1357,13 +1357,13 @@ static bool ipv6_good_nh(const struct fib6_nh *nh) int state = NUD_REACHABLE; struct neighbour *n; - rcu_read_lock_bh(); + rcu_read_lock(); n = __ipv6_neigh_lookup_noref_stub(nh->fib_nh_dev, &nh->fib_nh_gw6); if (n) state = READ_ONCE(n->nud_state); - rcu_read_unlock_bh(); + rcu_read_unlock(); return !!(state & NUD_VALID); } @@ -1373,14 +1373,14 @@ static bool ipv4_good_nh(const struct fib_nh *nh) int state = NUD_REACHABLE; struct neighbour *n; - rcu_read_lock_bh(); + rcu_read_lock(); n = __ipv4_neigh_lookup_noref(nh->fib_nh_dev, (__force u32)nh->fib_nh_gw4); if (n) state = READ_ONCE(n->nud_state); - rcu_read_unlock_bh(); + rcu_read_unlock(); return !!(state & NUD_VALID); } diff --git a/net/ipv4/route.c b/net/ipv4/route.c index 8ce5dd14d0a77..db8235ac1e166 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -416,7 +416,7 @@ static struct neighbour *ipv4_neigh_lookup(const struct dst_entry *dst, struct net_device *dev = dst->dev; struct neighbour *n; - rcu_read_lock_bh(); + rcu_read_lock(); if (likely(rt->rt_gw_family == AF_INET)) { n = ip_neigh_gw4(dev, rt->rt_gw4); @@ -432,7 +432,7 @@ static struct neighbour *ipv4_neigh_lookup(const struct dst_entry *dst, if (!IS_ERR(n) && !refcount_inc_not_zero(&n->refcnt)) n = NULL; - rcu_read_unlock_bh(); + rcu_read_unlock(); return n; } diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c index d2d32a37cd164..82d01967faccd 100644 --- a/net/ipv6/addrconf.c +++ b/net/ipv6/addrconf.c @@ -1033,7 +1033,7 @@ static int ipv6_add_addr_hash(struct net_device *dev, struct inet6_ifaddr *ifa) unsigned int hash = inet6_addr_hash(dev_net(dev), &ifa->addr); int err = 0; - spin_lock(&addrconf_hash_lock); + spin_lock_bh(&addrconf_hash_lock); /* Ignore adding duplicate addresses on an interface */ if (ipv6_chk_same_addr(dev_net(dev), &ifa->addr, dev, hash)) { @@ -1043,7 +1043,7 @@ static int ipv6_add_addr_hash(struct net_device *dev, struct inet6_ifaddr *ifa) hlist_add_head_rcu(&ifa->addr_lst, &inet6_addr_lst[hash]); } - spin_unlock(&addrconf_hash_lock); + spin_unlock_bh(&addrconf_hash_lock); return err; } @@ -1145,15 +1145,15 @@ ipv6_add_addr(struct inet6_dev *idev, struct ifa6_config *cfg, /* For caller */ refcount_set(&ifa->refcnt, 1); - rcu_read_lock_bh(); + rcu_read_lock(); err = ipv6_add_addr_hash(idev->dev, ifa); if (err < 0) { - rcu_read_unlock_bh(); + rcu_read_unlock(); goto out; } - write_lock(&idev->lock); + write_lock_bh(&idev->lock); /* Add to inet6_dev unicast addr list. */ ipv6_link_dev_addr(idev, ifa); @@ -1164,9 +1164,9 @@ ipv6_add_addr(struct inet6_dev *idev, struct ifa6_config *cfg, } in6_ifa_hold(ifa); - write_unlock(&idev->lock); + write_unlock_bh(&idev->lock); - rcu_read_unlock_bh(); + rcu_read_unlock(); inet6addr_notifier_call_chain(NETDEV_UP, ifa); out: diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c index 737d43441e6fd..23e8c08ece4ee 100644 --- a/net/ipv6/ip6_output.c +++ b/net/ipv6/ip6_output.c @@ -123,7 +123,7 @@ static int ip6_finish_output2(struct net *net, struct sock *sk, struct sk_buff * IP6_UPD_PO_STATS(net, idev, IPSTATS_MIB_OUT, skb->len); - rcu_read_lock_bh(); + rcu_read_lock(); nexthop = rt6_nexthop((struct rt6_info *)dst, daddr); neigh = __ipv6_neigh_lookup_noref(dev, nexthop); @@ -131,7 +131,7 @@ static int ip6_finish_output2(struct net *net, struct sock *sk, struct sk_buff * if (unlikely(!neigh)) neigh = __neigh_create(&nd_tbl, nexthop, dev, false); if (IS_ERR(neigh)) { - rcu_read_unlock_bh(); + rcu_read_unlock(); IP6_INC_STATS(net, idev, IPSTATS_MIB_OUTNOROUTES); kfree_skb_reason(skb, SKB_DROP_REASON_NEIGH_CREATEFAIL); return -EINVAL; @@ -139,7 +139,7 @@ static int ip6_finish_output2(struct net *net, struct sock *sk, struct sk_buff * } sock_confirm_neigh(skb, neigh); ret = neigh_output(neigh, skb, false); - rcu_read_unlock_bh(); + rcu_read_unlock(); return ret; } @@ -1167,11 +1167,11 @@ static int ip6_dst_lookup_tail(struct net *net, const struct sock *sk, * dst entry of the nexthop router */ rt = (struct rt6_info *) *dst; - rcu_read_lock_bh(); + rcu_read_lock(); n = __ipv6_neigh_lookup_noref(rt->dst.dev, rt6_nexthop(rt, &fl6->daddr)); err = n && !(READ_ONCE(n->nud_state) & NUD_VALID) ? -EINVAL : 0; - rcu_read_unlock_bh(); + rcu_read_unlock(); if (err) { struct inet6_ifaddr *ifp; diff --git a/net/ipv6/route.c b/net/ipv6/route.c index db5a3c6645471..2d70c8ae15e20 100644 --- a/net/ipv6/route.c +++ b/net/ipv6/route.c @@ -639,7 +639,7 @@ static void rt6_probe(struct fib6_nh *fib6_nh) nh_gw = &fib6_nh->fib_nh_gw6; dev = fib6_nh->fib_nh_dev; - rcu_read_lock_bh(); + rcu_read_lock(); last_probe = READ_ONCE(fib6_nh->last_probe); idev = __in6_dev_get(dev); if (!idev) @@ -649,7 +649,7 @@ static void rt6_probe(struct fib6_nh *fib6_nh) if (READ_ONCE(neigh->nud_state) & NUD_VALID) goto out; - write_lock(&neigh->lock); + write_lock_bh(&neigh->lock); if (!(neigh->nud_state & NUD_VALID) && time_after(jiffies, neigh->updated + @@ -658,7 +658,7 @@ static void rt6_probe(struct fib6_nh *fib6_nh) if (work) __neigh_set_probe_once(neigh); } - write_unlock(&neigh->lock); + write_unlock_bh(&neigh->lock); } else if (time_after(jiffies, last_probe + READ_ONCE(idev->cnf.rtr_probe_interval))) { work = kmalloc(sizeof(*work), GFP_ATOMIC); @@ -676,7 +676,7 @@ static void rt6_probe(struct fib6_nh *fib6_nh) } out: - rcu_read_unlock_bh(); + rcu_read_unlock(); } #else static inline void rt6_probe(struct fib6_nh *fib6_nh) @@ -692,7 +692,7 @@ static enum rt6_nud_state rt6_check_neigh(const struct fib6_nh *fib6_nh) enum rt6_nud_state ret = RT6_NUD_FAIL_HARD; struct neighbour *neigh; - rcu_read_lock_bh(); + rcu_read_lock(); neigh = __ipv6_neigh_lookup_noref(fib6_nh->fib_nh_dev, &fib6_nh->fib_nh_gw6); if (neigh) { @@ -710,7 +710,7 @@ static enum rt6_nud_state rt6_check_neigh(const struct fib6_nh *fib6_nh) ret = IS_ENABLED(CONFIG_IPV6_ROUTER_PREF) ? RT6_NUD_SUCCEED : RT6_NUD_FAIL_DO_RR; } - rcu_read_unlock_bh(); + rcu_read_unlock(); return ret; } From 6c4dd0a4e9463546aa2977ca3ddf098cfe3eef16 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Marcin=20Wcis=C5=82o?= Date: Thu, 16 Jul 2026 20:04:50 +0200 Subject: [PATCH 05/18] net: remove rcu_dereference_bh_rtnl() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit jira VULN-162723 cve-pre CVE-2025-40158 commit-author Eric Dumazet commit fe602c87df1b6927562f4ee61edd851bb9578a49 This helper is no longer used in the tree. Signed-off-by: Eric Dumazet Signed-off-by: Jakub Kicinski (cherry picked from commit fe602c87df1b6927562f4ee61edd851bb9578a49) Signed-off-by: Marcin Wcisło --- include/linux/rtnetlink.h | 10 ---------- 1 file changed, 10 deletions(-) diff --git a/include/linux/rtnetlink.h b/include/linux/rtnetlink.h index b1b6e68942cb0..cdfc897f1e3c6 100644 --- a/include/linux/rtnetlink.h +++ b/include/linux/rtnetlink.h @@ -70,16 +70,6 @@ static inline bool lockdep_rtnl_is_held(void) #define rcu_dereference_rtnl(p) \ rcu_dereference_check(p, lockdep_rtnl_is_held()) -/** - * rcu_dereference_bh_rtnl - rcu_dereference_bh with debug checking - * @p: The pointer to read, prior to dereference - * - * Do an rcu_dereference_bh(p), but check caller either holds rcu_read_lock_bh() - * or RTNL. Note : Please prefer rtnl_dereference() or rcu_dereference_bh() - */ -#define rcu_dereference_bh_rtnl(p) \ - rcu_dereference_bh_check(p, lockdep_rtnl_is_held()) - /** * rtnl_dereference - fetch RCU pointer when updates are prevented by RTNL * @p: The pointer to read, prior to dereferencing From d2f7af6709f1c53c77873d9dabff3a4d03874ffd Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Marcin=20Wcis=C5=82o?= Date: Thu, 16 Jul 2026 20:04:51 +0200 Subject: [PATCH 06/18] ipv6: remove nexthop_fib6_nh_bh() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit jira VULN-162723 cve-pre CVE-2025-40158 commit-author Eric Dumazet commit ef1148d4487438a3408d6face2a8360d91b4af70 After blamed commit, nexthop_fib6_nh_bh() and nexthop_fib6_nh() are the same. Delete nexthop_fib6_nh_bh(), and convert /proc/net/ipv6_route to standard rcu to avoid this splat: [ 5723.180080] WARNING: suspicious RCU usage [ 5723.180083] ----------------------------- [ 5723.180084] include/net/nexthop.h:516 suspicious rcu_dereference_check() usage! [ 5723.180086] other info that might help us debug this: [ 5723.180087] rcu_scheduler_active = 2, debug_locks = 1 [ 5723.180089] 2 locks held by cat/55856: [ 5723.180091] #0: ffff9440a582afa8 (&p->lock){+.+.}-{3:3}, at: seq_read_iter (fs/seq_file.c:188) [ 5723.180100] #1: ffffffffaac07040 (rcu_read_lock_bh){....}-{1:2}, at: rcu_lock_acquire (include/linux/rcupdate.h:326) [ 5723.180109] stack backtrace: [ 5723.180111] CPU: 14 PID: 55856 Comm: cat Tainted: G S I 6.3.0-dbx-DEV #528 [ 5723.180115] Call Trace: [ 5723.180117] [ 5723.180119] dump_stack_lvl (lib/dump_stack.c:107) [ 5723.180124] dump_stack (lib/dump_stack.c:114) [ 5723.180126] lockdep_rcu_suspicious (include/linux/context_tracking.h:122) [ 5723.180132] ipv6_route_seq_show (include/net/nexthop.h:?) [ 5723.180135] ? ipv6_route_seq_next (net/ipv6/ip6_fib.c:2605) [ 5723.180140] seq_read_iter (fs/seq_file.c:272) [ 5723.180145] seq_read (fs/seq_file.c:163) [ 5723.180151] proc_reg_read (fs/proc/inode.c:316 fs/proc/inode.c:328) [ 5723.180155] vfs_read (fs/read_write.c:468) [ 5723.180160] ? up_read (kernel/locking/rwsem.c:1617) [ 5723.180164] ksys_read (fs/read_write.c:613) [ 5723.180168] __x64_sys_read (fs/read_write.c:621) [ 5723.180170] do_syscall_64 (arch/x86/entry/common.c:?) [ 5723.180174] entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:120) [ 5723.180177] RIP: 0033:0x7fa455677d2a Fixes: 09eed1192cec ("neighbour: switch to standard rcu, instead of rcu_bh") Reported-by: syzbot Signed-off-by: Eric Dumazet Reviewed-by: David Ahern Link: https://lore.kernel.org/r/20230510154646.370659-1-edumazet@google.com Signed-off-by: Jakub Kicinski (cherry picked from commit ef1148d4487438a3408d6face2a8360d91b4af70) Signed-off-by: Marcin Wcisło --- include/net/nexthop.h | 23 ----------------------- net/ipv6/ip6_fib.c | 16 ++++++++-------- 2 files changed, 8 insertions(+), 31 deletions(-) diff --git a/include/net/nexthop.h b/include/net/nexthop.h index f3b0706ee8c72..79f8457768481 100644 --- a/include/net/nexthop.h +++ b/include/net/nexthop.h @@ -532,29 +532,6 @@ static inline struct fib6_nh *nexthop_fib6_nh(struct nexthop *nh) return NULL; } -/* Variant of nexthop_fib6_nh(). - * Caller should either hold rcu_read_lock(), or RTNL. - */ -static inline struct fib6_nh *nexthop_fib6_nh_bh(struct nexthop *nh) -{ - struct nh_info *nhi; - - if (nh->is_group) { - struct nh_group *nh_grp; - - nh_grp = rcu_dereference_rtnl(nh->nh_grp); - nh = nexthop_mpath_select(nh_grp, 0); - if (!nh) - return NULL; - } - - nhi = rcu_dereference_rtnl(nh->nh_info); - if (nhi->family == AF_INET6) - return &nhi->fib6_nh; - - return NULL; -} - static inline struct net_device *fib6_info_nh_dev(struct fib6_info *f6i) { struct fib6_nh *fib6_nh; diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c index 410cec4723543..7f4f00c4b3923 100644 --- a/net/ipv6/ip6_fib.c +++ b/net/ipv6/ip6_fib.c @@ -2499,7 +2499,7 @@ static int ipv6_route_native_seq_show(struct seq_file *seq, void *v) const struct net_device *dev; if (rt->nh) - fib6_nh = nexthop_fib6_nh_bh(rt->nh); + fib6_nh = nexthop_fib6_nh(rt->nh); seq_printf(seq, "%pi6 %02x ", &rt->fib6_dst.addr, rt->fib6_dst.plen); @@ -2564,14 +2564,14 @@ static struct fib6_table *ipv6_route_seq_next_table(struct fib6_table *tbl, if (tbl) { h = (tbl->tb6_id & (FIB6_TABLE_HASHSZ - 1)) + 1; - node = rcu_dereference_bh(hlist_next_rcu(&tbl->tb6_hlist)); + node = rcu_dereference(hlist_next_rcu(&tbl->tb6_hlist)); } else { h = 0; node = NULL; } while (!node && h < FIB6_TABLE_HASHSZ) { - node = rcu_dereference_bh( + node = rcu_dereference( hlist_first_rcu(&net->ipv6.fib_table_hash[h++])); } return hlist_entry_safe(node, struct fib6_table, tb6_hlist); @@ -2601,7 +2601,7 @@ static void *ipv6_route_seq_next(struct seq_file *seq, void *v, loff_t *pos) if (!v) goto iter_table; - n = rcu_dereference_bh(((struct fib6_info *)v)->fib6_next); + n = rcu_dereference(((struct fib6_info *)v)->fib6_next); if (n) return n; @@ -2627,12 +2627,12 @@ static void *ipv6_route_seq_next(struct seq_file *seq, void *v, loff_t *pos) } static void *ipv6_route_seq_start(struct seq_file *seq, loff_t *pos) - __acquires(RCU_BH) + __acquires(RCU) { struct net *net = seq_file_net(seq); struct ipv6_route_iter *iter = seq->private; - rcu_read_lock_bh(); + rcu_read_lock(); iter->tbl = ipv6_route_seq_next_table(NULL, net); iter->skip = *pos; @@ -2653,7 +2653,7 @@ static bool ipv6_route_iter_active(struct ipv6_route_iter *iter) } static void ipv6_route_native_seq_stop(struct seq_file *seq, void *v) - __releases(RCU_BH) + __releases(RCU) { struct net *net = seq_file_net(seq); struct ipv6_route_iter *iter = seq->private; @@ -2661,7 +2661,7 @@ static void ipv6_route_native_seq_stop(struct seq_file *seq, void *v) if (ipv6_route_iter_active(iter)) fib6_walker_unlink(net, &iter->w); - rcu_read_unlock_bh(); + rcu_read_unlock(); } #if IS_BUILTIN(CONFIG_IPV6) && defined(CONFIG_BPF_SYSCALL) From d44aadf1607558e8990b0068b18bcd189c958ddc Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Marcin=20Wcis=C5=82o?= Date: Thu, 16 Jul 2026 20:04:51 +0200 Subject: [PATCH 07/18] vrf: Fix lockdep splat in output path MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit jira VULN-162723 cve-pre CVE-2025-40158 commit-author Ido Schimmel commit 2033ab90380d46e0e9f0520fd6776a73d107fd95 Cited commit converted the neighbour code to use the standard RCU variant instead of the RCU-bh variant, but the VRF code still uses rcu_read_lock_bh() / rcu_read_unlock_bh() around the neighbour lookup code in its IPv4 and IPv6 output paths, resulting in lockdep splats [1][2]. Can be reproduced using [3]. Fix by switching to rcu_read_lock() / rcu_read_unlock(). [1] ============================= WARNING: suspicious RCU usage 6.5.0-rc1-custom-g9c099e6dbf98 #403 Not tainted ----------------------------- include/net/neighbour.h:302 suspicious rcu_dereference_check() usage! other info that might help us debug this: rcu_scheduler_active = 2, debug_locks = 1 2 locks held by ping/183: #0: ffff888105ea1d80 (sk_lock-AF_INET){+.+.}-{0:0}, at: raw_sendmsg+0xc6c/0x33c0 #1: ffffffff85b46820 (rcu_read_lock_bh){....}-{1:2}, at: vrf_output+0x2e3/0x2030 stack backtrace: CPU: 0 PID: 183 Comm: ping Not tainted 6.5.0-rc1-custom-g9c099e6dbf98 #403 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.2-1.fc37 04/01/2014 Call Trace: dump_stack_lvl+0xc1/0xf0 lockdep_rcu_suspicious+0x211/0x3b0 vrf_output+0x1380/0x2030 ip_push_pending_frames+0x125/0x2a0 raw_sendmsg+0x200d/0x33c0 inet_sendmsg+0xa2/0xe0 __sys_sendto+0x2aa/0x420 __x64_sys_sendto+0xe5/0x1c0 do_syscall_64+0x38/0x80 entry_SYSCALL_64_after_hwframe+0x63/0xcd [2] ============================= WARNING: suspicious RCU usage 6.5.0-rc1-custom-g9c099e6dbf98 #403 Not tainted ----------------------------- include/net/neighbour.h:302 suspicious rcu_dereference_check() usage! other info that might help us debug this: rcu_scheduler_active = 2, debug_locks = 1 2 locks held by ping6/182: #0: ffff888114b63000 (sk_lock-AF_INET6){+.+.}-{0:0}, at: rawv6_sendmsg+0x1602/0x3e50 #1: ffffffff85b46820 (rcu_read_lock_bh){....}-{1:2}, at: vrf_output6+0xe9/0x1310 stack backtrace: CPU: 0 PID: 182 Comm: ping6 Not tainted 6.5.0-rc1-custom-g9c099e6dbf98 #403 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.2-1.fc37 04/01/2014 Call Trace: dump_stack_lvl+0xc1/0xf0 lockdep_rcu_suspicious+0x211/0x3b0 vrf_output6+0xd32/0x1310 ip6_local_out+0xb4/0x1a0 ip6_send_skb+0xbc/0x340 ip6_push_pending_frames+0xe5/0x110 rawv6_sendmsg+0x2e6e/0x3e50 inet_sendmsg+0xa2/0xe0 __sys_sendto+0x2aa/0x420 __x64_sys_sendto+0xe5/0x1c0 do_syscall_64+0x38/0x80 entry_SYSCALL_64_after_hwframe+0x63/0xcd [3] #!/bin/bash ip link add name vrf-red up numtxqueues 2 type vrf table 10 ip link add name swp1 up master vrf-red type dummy ip address add 192.0.2.1/24 dev swp1 ip address add 2001:db8:1::1/64 dev swp1 ip neigh add 192.0.2.2 lladdr 00:11:22:33:44:55 nud perm dev swp1 ip neigh add 2001:db8:1::2 lladdr 00:11:22:33:44:55 nud perm dev swp1 ip vrf exec vrf-red ping 192.0.2.2 -c 1 &> /dev/null ip vrf exec vrf-red ping6 2001:db8:1::2 -c 1 &> /dev/null Fixes: 09eed1192cec ("neighbour: switch to standard rcu, instead of rcu_bh") Reported-by: Naresh Kamboju Link: https://lore.kernel.org/netdev/CA+G9fYtEr-=GbcXNDYo3XOkwR+uYgehVoDjsP0pFLUpZ_AZcyg@mail.gmail.com/ Signed-off-by: Ido Schimmel Reviewed-by: David Ahern Reviewed-by: Eric Dumazet Link: https://lore.kernel.org/r/20230715153605.4068066-1-idosch@nvidia.com Signed-off-by: Paolo Abeni (cherry picked from commit 2033ab90380d46e0e9f0520fd6776a73d107fd95) Signed-off-by: Marcin Wcisło --- drivers/net/vrf.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/drivers/net/vrf.c b/drivers/net/vrf.c index ce180a1d30eed..c1dc2e70d594a 100644 --- a/drivers/net/vrf.c +++ b/drivers/net/vrf.c @@ -654,7 +654,7 @@ static int vrf_finish_output6(struct net *net, struct sock *sk, skb->protocol = htons(ETH_P_IPV6); skb->dev = dev; - rcu_read_lock_bh(); + rcu_read_lock(); nexthop = rt6_nexthop((struct rt6_info *)dst, &ipv6_hdr(skb)->daddr); neigh = __ipv6_neigh_lookup_noref(dst->dev, nexthop); if (unlikely(!neigh)) @@ -662,10 +662,10 @@ static int vrf_finish_output6(struct net *net, struct sock *sk, if (!IS_ERR(neigh)) { sock_confirm_neigh(skb, neigh); ret = neigh_output(neigh, skb, false); - rcu_read_unlock_bh(); + rcu_read_unlock(); return ret; } - rcu_read_unlock_bh(); + rcu_read_unlock(); IP6_INC_STATS(dev_net(dst->dev), ip6_dst_idev(dst), IPSTATS_MIB_OUTNOROUTES); @@ -879,7 +879,7 @@ static int vrf_finish_output(struct net *net, struct sock *sk, struct sk_buff *s } } - rcu_read_lock_bh(); + rcu_read_lock(); neigh = ip_neigh_for_gw(rt, skb, &is_v6gw); if (!IS_ERR(neigh)) { @@ -888,11 +888,11 @@ static int vrf_finish_output(struct net *net, struct sock *sk, struct sk_buff *s sock_confirm_neigh(skb, neigh); /* if crossing protocols, can not use the cached header */ ret = neigh_output(neigh, skb, is_v6gw); - rcu_read_unlock_bh(); + rcu_read_unlock(); return ret; } - rcu_read_unlock_bh(); + rcu_read_unlock(); vrf_tx_error(skb->dev, skb); return -EINVAL; } From d18e8d6c2429c8f2597bf8f9ed7c36d7c682abfe Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Marcin=20Wcis=C5=82o?= Date: Thu, 16 Jul 2026 20:04:52 +0200 Subject: [PATCH 08/18] bpf: Fix mismatched RCU unlock flavour in bpf_out_neigh_v6 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit jira VULN-162723 cve-pre CVE-2025-40158 commit-author Jiawei Ye commit fb86c42a2a5d44e849ddfbc98b8d2f4f40d36ee3 In the bpf_out_neigh_v6 function, rcu_read_lock() is used to begin an RCU read-side critical section. However, when unlocking, one branch incorrectly uses a different RCU unlock flavour rcu_read_unlock_bh() instead of rcu_read_unlock(). This mismatch in RCU locking flavours can lead to unexpected behavior and potential concurrency issues. This possible bug was identified using a static analysis tool developed by myself, specifically designed to detect RCU-related issues. This patch corrects the mismatched unlock flavour by replacing the incorrect rcu_read_unlock_bh() with the appropriate rcu_read_unlock(), ensuring that the RCU critical section is properly exited. This change prevents potential synchronization issues and aligns with proper RCU usage patterns. Fixes: 09eed1192cec ("neighbour: switch to standard rcu, instead of rcu_bh") Signed-off-by: Jiawei Ye Acked-by: Yonghong Song Link: https://lore.kernel.org/r/tencent_CFD3D1C3D68B45EA9F52D8EC76D2C4134306@qq.com Signed-off-by: Martin KaFai Lau (cherry picked from commit fb86c42a2a5d44e849ddfbc98b8d2f4f40d36ee3) Signed-off-by: Marcin Wcisło --- net/core/filter.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/core/filter.c b/net/core/filter.c index 92434a04ec805..ccdabef65e527 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -2227,7 +2227,7 @@ static int bpf_out_neigh_v6(struct net *net, struct sk_buff *skb, rcu_read_unlock(); return ret; } - rcu_read_unlock_bh(); + rcu_read_unlock(); if (dst) IP6_INC_STATS(net, ip6_dst_idev(dst), IPSTATS_MIB_OUTNOROUTES); out_drop: From a0d131ee973b35bda856b9fb0113e7f84bee8397 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Marcin=20Wcis=C5=82o?= Date: Thu, 16 Jul 2026 20:04:52 +0200 Subject: [PATCH 09/18] net: dst: add four helpers to annotate data-races around dst->dev MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit jira VULN-162719 cve-pre CVE-2025-40170 commit-author Eric Dumazet commit 88fe14253e181878c2ddb51a298ae8c468a63010 upstream-diff Used CentOS 9 backport 098485bd7555a047d4c54974c72fcc8e62f97294 for a clean pick dst->dev is read locklessly in many contexts, and written in dst_dev_put(). Fixing all the races is going to need many changes. We probably will have to add full RCU protection. Add three helpers to ease this painful process. static inline struct net_device *dst_dev(const struct dst_entry *dst) { return READ_ONCE(dst->dev); } static inline struct net_device *skb_dst_dev(const struct sk_buff *skb) { return dst_dev(skb_dst(skb)); } static inline struct net *skb_dst_dev_net(const struct sk_buff *skb) { return dev_net(skb_dst_dev(skb)); } static inline struct net *skb_dst_dev_net_rcu(const struct sk_buff *skb) { return dev_net_rcu(skb_dst_dev(skb)); } Fixes: 4a6ce2b6f2ec ("net: introduce a new function dst_dev_put()") Signed-off-by: Eric Dumazet Reviewed-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20250630121934.3399505-7-edumazet@google.com Signed-off-by: Jakub Kicinski (cherry picked from commit 098485bd7555a047d4c54974c72fcc8e62f97294) Signed-off-by: Marcin Wcisło --- include/net/dst.h | 20 ++++++++++++++++++++ net/core/dst.c | 4 ++-- net/core/sock.c | 8 ++++---- 3 files changed, 26 insertions(+), 6 deletions(-) diff --git a/include/net/dst.h b/include/net/dst.h index b9a7b9ce719e1..e5fc34e2fd2b8 100644 --- a/include/net/dst.h +++ b/include/net/dst.h @@ -579,6 +579,26 @@ static inline void skb_dst_update_pmtu_no_confirm(struct sk_buff *skb, u32 mtu) dst->ops->update_pmtu(dst, NULL, skb, mtu, false); } +static inline struct net_device *dst_dev(const struct dst_entry *dst) +{ + return READ_ONCE(dst->dev); +} + +static inline struct net_device *skb_dst_dev(const struct sk_buff *skb) +{ + return dst_dev(skb_dst(skb)); +} + +static inline struct net *skb_dst_dev_net(const struct sk_buff *skb) +{ + return dev_net(skb_dst_dev(skb)); +} + +static inline struct net *skb_dst_dev_net_rcu(const struct sk_buff *skb) +{ + return dev_net_rcu(skb_dst_dev(skb)); +} + struct dst_entry *dst_blackhole_check(struct dst_entry *dst, u32 cookie); void dst_blackhole_update_pmtu(struct dst_entry *dst, struct sock *sk, struct sk_buff *skb, u32 mtu, bool confirm_neigh); diff --git a/net/core/dst.c b/net/core/dst.c index 00b1bacd87496..3bef7348fec14 100644 --- a/net/core/dst.c +++ b/net/core/dst.c @@ -152,7 +152,7 @@ void dst_dev_put(struct dst_entry *dst) dst->ops->ifdown(dst, dev, true); dst->input = dst_discard; dst->output = dst_discard_out; - dst->dev = blackhole_netdev; + WRITE_ONCE(dst->dev, blackhole_netdev); netdev_ref_replace(dev, blackhole_netdev, &dst->dev_tracker, GFP_ATOMIC); } @@ -257,7 +257,7 @@ unsigned int dst_blackhole_mtu(const struct dst_entry *dst) { unsigned int mtu = dst_metric_raw(dst, RTAX_MTU); - return mtu ? : dst->dev->mtu; + return mtu ? : dst_dev(dst)->mtu; } EXPORT_SYMBOL_GPL(dst_blackhole_mtu); diff --git a/net/core/sock.c b/net/core/sock.c index 56b31598b6ada..dadfe6547322f 100644 --- a/net/core/sock.c +++ b/net/core/sock.c @@ -2351,8 +2351,8 @@ static u32 sk_dst_gso_max_size(struct sock *sk, struct dst_entry *dst) !ipv6_addr_v4mapped(&sk->sk_v6_rcv_saddr)); #endif /* pairs with the WRITE_ONCE() in netif_set_gso(_ipv4)_max_size() */ - max_size = is_ipv6 ? READ_ONCE(dst->dev->gso_max_size) : - READ_ONCE(dst->dev->gso_ipv4_max_size); + max_size = is_ipv6 ? READ_ONCE(dst_dev(dst)->gso_max_size) : + READ_ONCE(dst_dev(dst)->gso_ipv4_max_size); if (max_size > GSO_LEGACY_MAX_SIZE && !sk_is_tcp(sk)) max_size = GSO_LEGACY_MAX_SIZE; @@ -2363,7 +2363,7 @@ void sk_setup_caps(struct sock *sk, struct dst_entry *dst) { u32 max_segs = 1; - sk->sk_route_caps = dst->dev->features; + sk->sk_route_caps = dst_dev(dst)->features; if (sk_is_tcp(sk)) sk->sk_route_caps |= NETIF_F_GSO; if (sk->sk_route_caps & NETIF_F_GSO) @@ -2377,7 +2377,7 @@ void sk_setup_caps(struct sock *sk, struct dst_entry *dst) sk->sk_route_caps |= NETIF_F_SG | NETIF_F_HW_CSUM; sk->sk_gso_max_size = sk_dst_gso_max_size(sk, dst); /* pairs with the WRITE_ONCE() in netif_set_gso_max_segs() */ - max_segs = max_t(u32, READ_ONCE(dst->dev->gso_max_segs), 1); + max_segs = max_t(u32, READ_ONCE(dst_dev(dst)->gso_max_segs), 1); } } sk->sk_gso_max_segs = max_segs; From c945036e3da8db055c418f01b78783a5bb4011cb Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Marcin=20Wcis=C5=82o?= Date: Thu, 16 Jul 2026 20:04:53 +0200 Subject: [PATCH 10/18] net: Add locking to protect skb->dev access in ip_output MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit jira VULN-162725 cve-pre CVE-2025-40135 commit-author Sharath Chandra Vurukala commit 1dbf1d590d10a6d1978e8184f8dfe20af22d680a upstream-diff Used CentOS 9 backport fb02c5a748f81d46ac611837d63f148721f36dec for a clean pick In ip_output() skb->dev is updated from the skb_dst(skb)->dev this can become invalid when the interface is unregistered and freed, Introduced new skb_dst_dev_rcu() function to be used instead of skb_dst_dev() within rcu_locks in ip_output.This will ensure that all the skb's associated with the dev being deregistered will be transnmitted out first, before freeing the dev. Given that ip_output() is called within an rcu_read_lock() critical section or from a bottom-half context, it is safe to introduce an RCU read-side critical section within it. Multiple panic call stacks were observed when UL traffic was run in concurrency with device deregistration from different functions, pasting one sample for reference. [496733.627565][T13385] Call trace: [496733.627570][T13385] bpf_prog_ce7c9180c3b128ea_cgroupskb_egres+0x24c/0x7f0 [496733.627581][T13385] __cgroup_bpf_run_filter_skb+0x128/0x498 [496733.627595][T13385] ip_finish_output+0xa4/0xf4 [496733.627605][T13385] ip_output+0x100/0x1a0 [496733.627613][T13385] ip_send_skb+0x68/0x100 [496733.627618][T13385] udp_send_skb+0x1c4/0x384 [496733.627625][T13385] udp_sendmsg+0x7b0/0x898 [496733.627631][T13385] inet_sendmsg+0x5c/0x7c [496733.627639][T13385] __sys_sendto+0x174/0x1e4 [496733.627647][T13385] __arm64_sys_sendto+0x28/0x3c [496733.627653][T13385] invoke_syscall+0x58/0x11c [496733.627662][T13385] el0_svc_common+0x88/0xf4 [496733.627669][T13385] do_el0_svc+0x2c/0xb0 [496733.627676][T13385] el0_svc+0x2c/0xa4 [496733.627683][T13385] el0t_64_sync_handler+0x68/0xb4 [496733.627689][T13385] el0t_64_sync+0x1a4/0x1a8 Changes in v3: - Replaced WARN_ON() with WARN_ON_ONCE(), as suggested by Willem de Bruijn. - Dropped legacy lines mistakenly pulled in from an outdated branch. Changes in v2: - Addressed review comments from Eric Dumazet - Used READ_ONCE() to prevent potential load/store tearing - Added skb_dst_dev_rcu() and used along with rcu_read_lock() in ip_output Signed-off-by: Sharath Chandra Vurukala Reviewed-by: Eric Dumazet Link: https://patch.msgid.link/20250730105118.GA26100@hu-sharathv-hyd.qualcomm.com Signed-off-by: Jakub Kicinski (cherry picked from commit fb02c5a748f81d46ac611837d63f148721f36dec) Signed-off-by: Marcin Wcisło --- include/net/dst.h | 12 ++++++++++++ net/ipv4/ip_output.c | 15 ++++++++++----- 2 files changed, 22 insertions(+), 5 deletions(-) diff --git a/include/net/dst.h b/include/net/dst.h index e5fc34e2fd2b8..d1fcd3e5ec5ff 100644 --- a/include/net/dst.h +++ b/include/net/dst.h @@ -584,11 +584,23 @@ static inline struct net_device *dst_dev(const struct dst_entry *dst) return READ_ONCE(dst->dev); } +static inline struct net_device *dst_dev_rcu(const struct dst_entry *dst) +{ + /* In the future, use rcu_dereference(dst->dev) */ + WARN_ON_ONCE(!rcu_read_lock_held()); + return READ_ONCE(dst->dev); +} + static inline struct net_device *skb_dst_dev(const struct sk_buff *skb) { return dst_dev(skb_dst(skb)); } +static inline struct net_device *skb_dst_dev_rcu(const struct sk_buff *skb) +{ + return dst_dev_rcu(skb_dst(skb)); +} + static inline struct net *skb_dst_dev_net(const struct sk_buff *skb) { return dev_net(skb_dst_dev(skb)); diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c index 4d5c3d86d25c9..a6506a81b81d9 100644 --- a/net/ipv4/ip_output.c +++ b/net/ipv4/ip_output.c @@ -425,15 +425,20 @@ int ip_mc_output(struct net *net, struct sock *sk, struct sk_buff *skb) int ip_output(struct net *net, struct sock *sk, struct sk_buff *skb) { - struct net_device *dev = skb_dst(skb)->dev, *indev = skb->dev; + struct net_device *dev, *indev = skb->dev; + int ret_val; + rcu_read_lock(); + dev = skb_dst_dev_rcu(skb); skb->dev = dev; skb->protocol = htons(ETH_P_IP); - return NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING, - net, sk, skb, indev, dev, - ip_finish_output, - !(IPCB(skb)->flags & IPSKB_REROUTED)); + ret_val = NF_HOOK_COND(NFPROTO_IPV4, NF_INET_POST_ROUTING, + net, sk, skb, indev, dev, + ip_finish_output, + !(IPCB(skb)->flags & IPSKB_REROUTED)); + rcu_read_unlock(); + return ret_val; } EXPORT_SYMBOL(ip_output); From 32f08e8794b19f4bf654662696b7cce477bc5364 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Marcin=20Wcis=C5=82o?= Date: Thu, 16 Jul 2026 20:04:53 +0200 Subject: [PATCH 11/18] ipv4: use RCU protection in __ip_rt_update_pmtu() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit jira VULN-162081 cve CVE-2025-21766 commit-author Eric Dumazet commit 139512191bd06f1b496117c76372b2ce372c9a41 upstream-diff Used CentOS 9 backport fd7e9d21f4fa35270f40feb436ad53deebbcc0ee for a clean pick __ip_rt_update_pmtu() must use RCU protection to make sure the net structure it reads does not disappear. Fixes: 2fbc6e89b2f1 ("ipv4: Update exception handling for multipath routes via same device") Fixes: 1de6b15a434c ("Namespaceify min_pmtu sysctl") Signed-off-by: Eric Dumazet Link: https://patch.msgid.link/20250205155120.1676781-8-edumazet@google.com Signed-off-by: Jakub Kicinski (cherry picked from commit fd7e9d21f4fa35270f40feb436ad53deebbcc0ee) Signed-off-by: Marcin Wcisło --- net/ipv4/route.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/net/ipv4/route.c b/net/ipv4/route.c index db8235ac1e166..2e29bf3f1c014 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -1022,9 +1022,9 @@ out: kfree_skb_reason(skb, reason); static void __ip_rt_update_pmtu(struct rtable *rt, struct flowi4 *fl4, u32 mtu) { struct dst_entry *dst = &rt->dst; - struct net *net = dev_net(dst->dev); struct fib_result res; bool lock = false; + struct net *net; u32 old_mtu; if (ip_mtu_locked(dst)) @@ -1034,6 +1034,8 @@ static void __ip_rt_update_pmtu(struct rtable *rt, struct flowi4 *fl4, u32 mtu) if (old_mtu < mtu) return; + rcu_read_lock(); + net = dev_net_rcu(dst->dev); if (mtu < ip_rt_min_pmtu) { lock = true; mtu = min(old_mtu, ip_rt_min_pmtu); @@ -1041,9 +1043,8 @@ static void __ip_rt_update_pmtu(struct rtable *rt, struct flowi4 *fl4, u32 mtu) if (rt->rt_pmtu == mtu && !lock && time_before(jiffies, dst->expires - ip_rt_mtu_expires / 2)) - return; + goto out; - rcu_read_lock(); if (fib_lookup(net, fl4, &res, 0) == 0) { struct fib_nh_common *nhc; @@ -1052,6 +1053,7 @@ static void __ip_rt_update_pmtu(struct rtable *rt, struct flowi4 *fl4, u32 mtu) update_or_create_fnhe(nhc, fl4->daddr, 0, mtu, lock, jiffies + ip_rt_mtu_expires); } +out: rcu_read_unlock(); } From f590d33f9e28fe3247559544f5e6ba715de1e35c Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Marcin=20Wcis=C5=82o?= Date: Thu, 16 Jul 2026 20:04:54 +0200 Subject: [PATCH 12/18] net: dst: introduce dst->dev_rcu MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit jira VULN-162719 cve-pre CVE-2025-40170 commit-author Eric Dumazet commit caedcc5b6df1b2e2b5f39079e3369c1d4d5c5f50 upstream-diff Used CentOS 9 backport ca6810ffc83408a1dd36676447c35d0348ef0571 as a clean cherry-pick base. Used RH_KABI_REPLACE in `struct dst_entry' to silence the kABI checker. Originally the `struct net_device *dev' field was changed into a union of `struct net_device *dev' and `struct net_device __rcu *dev_rcu'. The latter has the same size and alignment as the former (this is actually checked statically by the RH_KABI_REPLACE macro), with the `__rcu' annotation serving only at compile time and being invisible to the binary output. The `dev_rcu' is therefore just an alias for the `dev' field. Followup of commit 88fe14253e18 ("net: dst: add four helpers to annotate data-races around dst->dev"). We want to gradually add explicit RCU protection to dst->dev, including lockdep support. Add an union to alias dst->dev_rcu and dst->dev. Add dst_dev_net_rcu() helper. Fixes: 4a6ce2b6f2ec ("net: introduce a new function dst_dev_put()") Signed-off-by: Eric Dumazet Reviewed-by: David Ahern Link: https://patch.msgid.link/20250828195823.3958522-2-edumazet@google.com Signed-off-by: Jakub Kicinski (cherry picked from commit d566795fc6a28cf9457511b428c86bb783ac7d7c) Signed-off-by: Marcin Wcisło --- include/net/dst.h | 18 +++++++++++++----- net/core/dst.c | 2 +- net/ipv4/route.c | 2 +- 3 files changed, 15 insertions(+), 7 deletions(-) diff --git a/include/net/dst.h b/include/net/dst.h index d1fcd3e5ec5ff..73d7978098998 100644 --- a/include/net/dst.h +++ b/include/net/dst.h @@ -26,7 +26,12 @@ struct sk_buff; struct dst_entry { - struct net_device *dev; + RH_KABI_REPLACE( + struct net_device *dev, + union { + struct net_device *dev; + struct net_device __rcu *dev_rcu; + }) struct dst_ops *ops; unsigned long _metrics; unsigned long expires; @@ -586,9 +591,12 @@ static inline struct net_device *dst_dev(const struct dst_entry *dst) static inline struct net_device *dst_dev_rcu(const struct dst_entry *dst) { - /* In the future, use rcu_dereference(dst->dev) */ - WARN_ON_ONCE(!rcu_read_lock_held()); - return READ_ONCE(dst->dev); + return rcu_dereference(dst->dev_rcu); +} + +static inline struct net *dst_dev_net_rcu(const struct dst_entry *dst) +{ + return dev_net_rcu(dst_dev_rcu(dst)); } static inline struct net_device *skb_dst_dev(const struct sk_buff *skb) @@ -608,7 +616,7 @@ static inline struct net *skb_dst_dev_net(const struct sk_buff *skb) static inline struct net *skb_dst_dev_net_rcu(const struct sk_buff *skb) { - return dev_net_rcu(skb_dst_dev(skb)); + return dev_net_rcu(skb_dst_dev_rcu(skb)); } struct dst_entry *dst_blackhole_check(struct dst_entry *dst, u32 cookie); diff --git a/net/core/dst.c b/net/core/dst.c index 3bef7348fec14..cc01dfb557070 100644 --- a/net/core/dst.c +++ b/net/core/dst.c @@ -152,7 +152,7 @@ void dst_dev_put(struct dst_entry *dst) dst->ops->ifdown(dst, dev, true); dst->input = dst_discard; dst->output = dst_discard_out; - WRITE_ONCE(dst->dev, blackhole_netdev); + rcu_assign_pointer(dst->dev_rcu, blackhole_netdev); netdev_ref_replace(dev, blackhole_netdev, &dst->dev_tracker, GFP_ATOMIC); } diff --git a/net/ipv4/route.c b/net/ipv4/route.c index 2e29bf3f1c014..3cf3f5b2aaa8d 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -1035,7 +1035,7 @@ static void __ip_rt_update_pmtu(struct rtable *rt, struct flowi4 *fl4, u32 mtu) return; rcu_read_lock(); - net = dev_net_rcu(dst->dev); + net = dst_dev_net_rcu(dst); if (mtu < ip_rt_min_pmtu) { lock = true; mtu = min(old_mtu, ip_rt_min_pmtu); From 6ecba7b3f91bc63633d37b4e780cd2ddf7850d3e Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Marcin=20Wcis=C5=82o?= Date: Thu, 16 Jul 2026 20:04:54 +0200 Subject: [PATCH 13/18] ipv6: use RCU in ip6_output() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit jira VULN-162723 cve CVE-2025-40158 commit-author Eric Dumazet commit 11709573cc4e48dc34c80fc7ab9ce5b159e29695 upstream-diff Used CentOS 9 backport 9b21011cae661b5f80f0ea5220b288f423d6df69 for a clean pick Use RCU in ip6_output() in order to use dst_dev_rcu() to prevent possible UAF. We can remove rcu_read_lock()/rcu_read_unlock() pairs from ip6_finish_output2(). Fixes: 4a6ce2b6f2ec ("net: introduce a new function dst_dev_put()") Signed-off-by: Eric Dumazet Reviewed-by: David Ahern Link: https://patch.msgid.link/20250828195823.3958522-5-edumazet@google.com Signed-off-by: Jakub Kicinski (cherry picked from commit 9b21011cae661b5f80f0ea5220b288f423d6df69) Signed-off-by: Marcin Wcisło --- net/ipv6/ip6_output.c | 30 ++++++++++++++++-------------- 1 file changed, 16 insertions(+), 14 deletions(-) diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c index 23e8c08ece4ee..9f7fca0d879fd 100644 --- a/net/ipv6/ip6_output.c +++ b/net/ipv6/ip6_output.c @@ -60,7 +60,7 @@ static int ip6_finish_output2(struct net *net, struct sock *sk, struct sk_buff *skb) { struct dst_entry *dst = skb_dst(skb); - struct net_device *dev = dst->dev; + struct net_device *dev = dst_dev_rcu(dst); struct inet6_dev *idev = ip6_dst_idev(dst); unsigned int hh_len = LL_RESERVED_SPACE(dev); const struct in6_addr *daddr, *nexthop; @@ -70,15 +70,12 @@ static int ip6_finish_output2(struct net *net, struct sock *sk, struct sk_buff * /* Be paranoid, rather than too clever. */ if (unlikely(hh_len > skb_headroom(skb)) && dev->header_ops) { - /* Make sure idev stays alive */ - rcu_read_lock(); + /* idev stays alive because we hold rcu_read_lock(). */ skb = skb_expand_head(skb, hh_len); if (!skb) { IP6_INC_STATS(net, idev, IPSTATS_MIB_OUTDISCARDS); - rcu_read_unlock(); return -ENOMEM; } - rcu_read_unlock(); } hdr = ipv6_hdr(skb); @@ -123,7 +120,6 @@ static int ip6_finish_output2(struct net *net, struct sock *sk, struct sk_buff * IP6_UPD_PO_STATS(net, idev, IPSTATS_MIB_OUT, skb->len); - rcu_read_lock(); nexthop = rt6_nexthop((struct rt6_info *)dst, daddr); neigh = __ipv6_neigh_lookup_noref(dev, nexthop); @@ -131,7 +127,6 @@ static int ip6_finish_output2(struct net *net, struct sock *sk, struct sk_buff * if (unlikely(!neigh)) neigh = __neigh_create(&nd_tbl, nexthop, dev, false); if (IS_ERR(neigh)) { - rcu_read_unlock(); IP6_INC_STATS(net, idev, IPSTATS_MIB_OUTNOROUTES); kfree_skb_reason(skb, SKB_DROP_REASON_NEIGH_CREATEFAIL); return -EINVAL; @@ -139,7 +134,6 @@ static int ip6_finish_output2(struct net *net, struct sock *sk, struct sk_buff * } sock_confirm_neigh(skb, neigh); ret = neigh_output(neigh, skb, false); - rcu_read_unlock(); return ret; } @@ -225,22 +219,30 @@ static int ip6_finish_output(struct net *net, struct sock *sk, struct sk_buff *s int ip6_output(struct net *net, struct sock *sk, struct sk_buff *skb) { - struct net_device *dev = skb_dst(skb)->dev, *indev = skb->dev; - struct inet6_dev *idev = ip6_dst_idev(skb_dst(skb)); + struct dst_entry *dst = skb_dst(skb); + struct net_device *dev, *indev = skb->dev; + struct inet6_dev *idev; + int ret; skb->protocol = htons(ETH_P_IPV6); + rcu_read_lock(); + dev = dst_dev_rcu(dst); + idev = ip6_dst_idev(dst); skb->dev = dev; if (unlikely(!idev || READ_ONCE(idev->cnf.disable_ipv6))) { IP6_INC_STATS(net, idev, IPSTATS_MIB_OUTDISCARDS); + rcu_read_unlock(); kfree_skb_reason(skb, SKB_DROP_REASON_IPV6DISABLED); return 0; } - return NF_HOOK_COND(NFPROTO_IPV6, NF_INET_POST_ROUTING, - net, sk, skb, indev, dev, - ip6_finish_output, - !(IP6CB(skb)->flags & IP6SKB_REROUTED)); + ret = NF_HOOK_COND(NFPROTO_IPV6, NF_INET_POST_ROUTING, + net, sk, skb, indev, dev, + ip6_finish_output, + !(IP6CB(skb)->flags & IP6SKB_REROUTED)); + rcu_read_unlock(); + return ret; } EXPORT_SYMBOL(ip6_output); From 83087430dfbec5ce4878a9026681863becb3ef94 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Marcin=20Wcis=C5=82o?= Date: Thu, 16 Jul 2026 20:04:55 +0200 Subject: [PATCH 14/18] ipv6: use RCU in ip6_xmit() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit jira VULN-162725 cve CVE-2025-40135 commit-author Eric Dumazet commit 9085e56501d93af9f2d7bd16f7fcfacdde47b99c upstream-diff Used CentOS 9 backport f37f7b3231da22922882bd67b4918788919216b8 for a clean pick Use RCU in ip6_xmit() in order to use dst_dev_rcu() to prevent possible UAF. Fixes: 4a6ce2b6f2ec ("net: introduce a new function dst_dev_put()") Signed-off-by: Eric Dumazet Reviewed-by: David Ahern Link: https://patch.msgid.link/20250828195823.3958522-4-edumazet@google.com Signed-off-by: Jakub Kicinski (cherry picked from commit f37f7b3231da22922882bd67b4918788919216b8) Signed-off-by: Marcin Wcisło --- net/ipv6/ip6_output.c | 35 +++++++++++++++++++++-------------- 1 file changed, 21 insertions(+), 14 deletions(-) diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c index 9f7fca0d879fd..eed7ac422b26d 100644 --- a/net/ipv6/ip6_output.c +++ b/net/ipv6/ip6_output.c @@ -263,35 +263,36 @@ bool ip6_autoflowlabel(struct net *net, const struct ipv6_pinfo *np) int ip6_xmit(const struct sock *sk, struct sk_buff *skb, struct flowi6 *fl6, __u32 mark, struct ipv6_txoptions *opt, int tclass, u32 priority) { - struct net *net = sock_net(sk); const struct ipv6_pinfo *np = inet6_sk(sk); struct in6_addr *first_hop = &fl6->daddr; struct dst_entry *dst = skb_dst(skb); - struct net_device *dev = dst->dev; struct inet6_dev *idev = ip6_dst_idev(dst); struct hop_jumbo_hdr *hop_jumbo; int hoplen = sizeof(*hop_jumbo); + struct net *net = sock_net(sk); unsigned int head_room; + struct net_device *dev; struct ipv6hdr *hdr; u8 proto = fl6->flowi6_proto; int seg_len = skb->len; - int hlimit = -1; + int ret, hlimit = -1; u32 mtu; + rcu_read_lock(); + + dev = dst_dev_rcu(dst); head_room = sizeof(struct ipv6hdr) + hoplen + LL_RESERVED_SPACE(dev); if (opt) head_room += opt->opt_nflen + opt->opt_flen; if (unlikely(head_room > skb_headroom(skb))) { - /* Make sure idev stays alive */ - rcu_read_lock(); + /* idev stays alive while we hold rcu_read_lock(). */ skb = skb_expand_head(skb, head_room); if (!skb) { IP6_INC_STATS(net, idev, IPSTATS_MIB_OUTDISCARDS); - rcu_read_unlock(); - return -ENOBUFS; + ret = -ENOBUFS; + goto unlock; } - rcu_read_unlock(); } if (opt) { @@ -353,17 +354,21 @@ int ip6_xmit(const struct sock *sk, struct sk_buff *skb, struct flowi6 *fl6, * skb to its handler for processing */ skb = l3mdev_ip6_out((struct sock *)sk, skb); - if (unlikely(!skb)) - return 0; + if (unlikely(!skb)) { + ret = 0; + goto unlock; + } /* hooks should never assume socket lock is held. * we promote our socket to non const */ - return NF_HOOK(NFPROTO_IPV6, NF_INET_LOCAL_OUT, - net, (struct sock *)sk, skb, NULL, dev, - dst_output); + ret = NF_HOOK(NFPROTO_IPV6, NF_INET_LOCAL_OUT, + net, (struct sock *)sk, skb, NULL, dev, + dst_output); + goto unlock; } + ret = -EMSGSIZE; skb->dev = dev; /* ipv6_local_error() does not require socket lock, * we promote our socket to non const @@ -372,7 +377,9 @@ int ip6_xmit(const struct sock *sk, struct sk_buff *skb, struct flowi6 *fl6, IP6_INC_STATS(net, idev, IPSTATS_MIB_FRAGFAILS); kfree_skb(skb); - return -EMSGSIZE; +unlock: + rcu_read_unlock(); + return ret; } EXPORT_SYMBOL(ip6_xmit); From ca7d49672ca02ab8551948c42bb843fb7802894d Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Marcin=20Wcis=C5=82o?= Date: Thu, 16 Jul 2026 20:04:55 +0200 Subject: [PATCH 15/18] net: ipv4: Consolidate ipv4_mtu and ip_dst_mtu_maybe_forward MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit jira VULN-162719 cve-pre CVE-2025-40170 commit-author Vadim Fedorenko commit ac6627a28dbfb5d96736544a00c3938fa7ea6dfb Consolidate IPv4 MTU code the same way it is done in IPv6 to have code aligned in both address families Signed-off-by: Vadim Fedorenko Reviewed-by: David Ahern Signed-off-by: David S. Miller (cherry picked from commit ac6627a28dbfb5d96736544a00c3938fa7ea6dfb) Signed-off-by: Marcin Wcisło --- include/net/ip.h | 22 ++++++++++++++++++---- net/ipv4/route.c | 21 +-------------------- 2 files changed, 19 insertions(+), 24 deletions(-) diff --git a/include/net/ip.h b/include/net/ip.h index 20b6017483099..f98661f56cbda 100644 --- a/include/net/ip.h +++ b/include/net/ip.h @@ -443,18 +443,32 @@ static inline bool ip_sk_ignore_df(const struct sock *sk) static inline unsigned int ip_dst_mtu_maybe_forward(const struct dst_entry *dst, bool forwarding) { + const struct rtable *rt = container_of(dst, struct rtable, dst); struct net *net = dev_net(dst->dev); unsigned int mtu; if (READ_ONCE(net->ipv4.sysctl_ip_fwd_use_pmtu) || ip_mtu_locked(dst) || - !forwarding) - return dst_mtu(dst); + !forwarding) { + mtu = rt->rt_pmtu; + if (mtu && time_before(jiffies, rt->dst.expires)) + goto out; + } /* 'forwarding = true' case should always honour route mtu */ mtu = dst_metric_raw(dst, RTAX_MTU); - if (!mtu) - mtu = min(READ_ONCE(dst->dev->mtu), IP_MAX_MTU); + if (mtu) + goto out; + + mtu = READ_ONCE(dst->dev->mtu); + + if (unlikely(ip_mtu_locked(dst))) { + if (rt->rt_uses_gateway && mtu > 576) + mtu = 576; + } + +out: + mtu = min_t(unsigned int, mtu, IP_MAX_MTU); return mtu - lwtunnel_headroom(dst->lwtstate, mtu); } diff --git a/net/ipv4/route.c b/net/ipv4/route.c index 3cf3f5b2aaa8d..1735b782fdeb6 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -1329,26 +1329,7 @@ static unsigned int ipv4_default_advmss(const struct dst_entry *dst) INDIRECT_CALLABLE_SCOPE unsigned int ipv4_mtu(const struct dst_entry *dst) { - const struct rtable *rt = (const struct rtable *)dst; - unsigned int mtu = rt->rt_pmtu; - - if (!mtu || time_after_eq(jiffies, rt->dst.expires)) - mtu = dst_metric_raw(dst, RTAX_MTU); - - if (mtu) - goto out; - - mtu = READ_ONCE(dst->dev->mtu); - - if (unlikely(ip_mtu_locked(dst))) { - if (rt->rt_uses_gateway && mtu > 576) - mtu = 576; - } - -out: - mtu = min_t(unsigned int, mtu, IP_MAX_MTU); - - return mtu - lwtunnel_headroom(dst->lwtstate, mtu); + return ip_dst_mtu_maybe_forward(dst, false); } EXPORT_INDIRECT_CALLABLE(ipv4_mtu); From 36974d428d39c01793920aaf63607d028e288bc9 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Marcin=20Wcis=C5=82o?= Date: Thu, 16 Jul 2026 20:04:56 +0200 Subject: [PATCH 16/18] ipv4: use RCU protection in ip_dst_mtu_maybe_forward() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit jira VULN-162719 cve-pre CVE-2025-40170 commit-author Eric Dumazet commit 071d8012869b6af352acca346ade13e7be90a49f upstream-diff Used CentOS 9 backport 4ea98f09499595e3b4b380e5ef60c2c9563b06be for a clean pick ip_dst_mtu_maybe_forward() must use RCU protection to make sure the net structure it reads does not disappear. Fixes: f87c10a8aa1e8 ("ipv4: introduce ip_dst_mtu_maybe_forward and protect forwarding path against pmtu spoofing") Signed-off-by: Eric Dumazet Reviewed-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20250205155120.1676781-4-edumazet@google.com Signed-off-by: Jakub Kicinski (cherry picked from commit 4ea98f09499595e3b4b380e5ef60c2c9563b06be) Signed-off-by: Marcin Wcisło --- include/net/ip.h | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) diff --git a/include/net/ip.h b/include/net/ip.h index f98661f56cbda..9cb1c8ae16da5 100644 --- a/include/net/ip.h +++ b/include/net/ip.h @@ -444,9 +444,12 @@ static inline unsigned int ip_dst_mtu_maybe_forward(const struct dst_entry *dst, bool forwarding) { const struct rtable *rt = container_of(dst, struct rtable, dst); - struct net *net = dev_net(dst->dev); - unsigned int mtu; + unsigned int mtu, res; + struct net *net; + + rcu_read_lock(); + net = dev_net_rcu(dst->dev); if (READ_ONCE(net->ipv4.sysctl_ip_fwd_use_pmtu) || ip_mtu_locked(dst) || !forwarding) { @@ -470,7 +473,11 @@ static inline unsigned int ip_dst_mtu_maybe_forward(const struct dst_entry *dst, out: mtu = min_t(unsigned int, mtu, IP_MAX_MTU); - return mtu - lwtunnel_headroom(dst->lwtstate, mtu); + res = mtu - lwtunnel_headroom(dst->lwtstate, mtu); + + rcu_read_unlock(); + + return res; } static inline unsigned int ip_skb_dst_mtu(struct sock *sk, From 153354c4cd9a8f5d2eb377d1cb49854fa3f7fdb8 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Marcin=20Wcis=C5=82o?= Date: Thu, 16 Jul 2026 20:04:56 +0200 Subject: [PATCH 17/18] ipv4: add RCU protection to ip4_dst_hoplimit() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit jira VULN-162719 cve-pre CVE-2025-40170 commit-author Eric Dumazet commit 469308552ca4560176cfc100e7ca84add1bebd7c ip4_dst_hoplimit() must use RCU protection to make sure the net structure it reads does not disappear. Fixes: fa50d974d104 ("ipv4: Namespaceify ip_default_ttl sysctl knob") Signed-off-by: Eric Dumazet Reviewed-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20250205155120.1676781-3-edumazet@google.com Signed-off-by: Jakub Kicinski (cherry picked from commit 469308552ca4560176cfc100e7ca84add1bebd7c) Signed-off-by: Marcin Wcisło --- include/net/route.h | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/include/net/route.h b/include/net/route.h index 13e1180741af8..51413bff76615 100644 --- a/include/net/route.h +++ b/include/net/route.h @@ -353,10 +353,15 @@ static inline int inet_iif(const struct sk_buff *skb) static inline int ip4_dst_hoplimit(const struct dst_entry *dst) { int hoplimit = dst_metric_raw(dst, RTAX_HOPLIMIT); - struct net *net = dev_net(dst->dev); - if (hoplimit == 0) + if (hoplimit == 0) { + const struct net *net; + + rcu_read_lock(); + net = dev_net_rcu(dst->dev); hoplimit = READ_ONCE(net->ipv4.sysctl_ip_default_ttl); + rcu_read_unlock(); + } return hoplimit; } From 35e5d7be677eca8d4a42d20d7ffb0254892b30df Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Marcin=20Wcis=C5=82o?= Date: Thu, 16 Jul 2026 20:04:57 +0200 Subject: [PATCH 18/18] net: use dst_dev_rcu() in sk_setup_caps() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit jira VULN-162719 cve CVE-2025-40170 commit-author Eric Dumazet commit 99a2ace61b211b0be861b07fbaa062fca4b58879 upstream-diff Used CentOS 9 backport acc5b1b3f6e937c219da6eff70f79f29c0c794e0 for a clean pick Use RCU to protect accesses to dst->dev from sk_setup_caps() and sk_dst_gso_max_size(). Also use dst_dev_rcu() in ip6_dst_mtu_maybe_forward(), and ip_dst_mtu_maybe_forward(). ip4_dst_hoplimit() can use dst_dev_net_rcu(). Fixes: 4a6ce2b6f2ec ("net: introduce a new function dst_dev_put()") Signed-off-by: Eric Dumazet Reviewed-by: David Ahern Link: https://patch.msgid.link/20250828195823.3958522-6-edumazet@google.com Signed-off-by: Jakub Kicinski (cherry picked from commit acc5b1b3f6e937c219da6eff70f79f29c0c794e0) Signed-off-by: Marcin Wcisło --- include/net/ip.h | 6 ++++-- include/net/ip6_route.h | 2 +- include/net/route.h | 2 +- net/core/sock.c | 16 ++++++++++------ 4 files changed, 16 insertions(+), 10 deletions(-) diff --git a/include/net/ip.h b/include/net/ip.h index 9cb1c8ae16da5..ab6e5263e0e43 100644 --- a/include/net/ip.h +++ b/include/net/ip.h @@ -444,12 +444,14 @@ static inline unsigned int ip_dst_mtu_maybe_forward(const struct dst_entry *dst, bool forwarding) { const struct rtable *rt = container_of(dst, struct rtable, dst); + const struct net_device *dev; unsigned int mtu, res; struct net *net; rcu_read_lock(); - net = dev_net_rcu(dst->dev); + dev = dst_dev_rcu(dst); + net = dev_net_rcu(dev); if (READ_ONCE(net->ipv4.sysctl_ip_fwd_use_pmtu) || ip_mtu_locked(dst) || !forwarding) { @@ -463,7 +465,7 @@ static inline unsigned int ip_dst_mtu_maybe_forward(const struct dst_entry *dst, if (mtu) goto out; - mtu = READ_ONCE(dst->dev->mtu); + mtu = READ_ONCE(dev->mtu); if (unlikely(ip_mtu_locked(dst))) { if (rt->rt_uses_gateway && mtu > 576) diff --git a/include/net/ip6_route.h b/include/net/ip6_route.h index cd3ecba4415af..6a26d702d8a2e 100644 --- a/include/net/ip6_route.h +++ b/include/net/ip6_route.h @@ -337,7 +337,7 @@ static inline unsigned int ip6_dst_mtu_forward(const struct dst_entry *dst) mtu = IPV6_MIN_MTU; rcu_read_lock(); - idev = __in6_dev_get(dst->dev); + idev = __in6_dev_get(dst_dev_rcu(dst)); if (idev) mtu = READ_ONCE(idev->cnf.mtu6); rcu_read_unlock(); diff --git a/include/net/route.h b/include/net/route.h index 51413bff76615..fd215a831ef87 100644 --- a/include/net/route.h +++ b/include/net/route.h @@ -358,7 +358,7 @@ static inline int ip4_dst_hoplimit(const struct dst_entry *dst) const struct net *net; rcu_read_lock(); - net = dev_net_rcu(dst->dev); + net = dst_dev_net_rcu(dst); hoplimit = READ_ONCE(net->ipv4.sysctl_ip_default_ttl); rcu_read_unlock(); } diff --git a/net/core/sock.c b/net/core/sock.c index dadfe6547322f..fa79bc7ad15fa 100644 --- a/net/core/sock.c +++ b/net/core/sock.c @@ -2341,7 +2341,7 @@ void sk_free_unlock_clone(struct sock *sk) } EXPORT_SYMBOL_GPL(sk_free_unlock_clone); -static u32 sk_dst_gso_max_size(struct sock *sk, struct dst_entry *dst) +static u32 sk_dst_gso_max_size(struct sock *sk, const struct net_device *dev) { bool is_ipv6 = false; u32 max_size; @@ -2351,8 +2351,8 @@ static u32 sk_dst_gso_max_size(struct sock *sk, struct dst_entry *dst) !ipv6_addr_v4mapped(&sk->sk_v6_rcv_saddr)); #endif /* pairs with the WRITE_ONCE() in netif_set_gso(_ipv4)_max_size() */ - max_size = is_ipv6 ? READ_ONCE(dst_dev(dst)->gso_max_size) : - READ_ONCE(dst_dev(dst)->gso_ipv4_max_size); + max_size = is_ipv6 ? READ_ONCE(dev->gso_max_size) : + READ_ONCE(dev->gso_ipv4_max_size); if (max_size > GSO_LEGACY_MAX_SIZE && !sk_is_tcp(sk)) max_size = GSO_LEGACY_MAX_SIZE; @@ -2361,9 +2361,12 @@ static u32 sk_dst_gso_max_size(struct sock *sk, struct dst_entry *dst) void sk_setup_caps(struct sock *sk, struct dst_entry *dst) { + const struct net_device *dev; u32 max_segs = 1; - sk->sk_route_caps = dst_dev(dst)->features; + rcu_read_lock(); + dev = dst_dev_rcu(dst); + sk->sk_route_caps = dev->features; if (sk_is_tcp(sk)) sk->sk_route_caps |= NETIF_F_GSO; if (sk->sk_route_caps & NETIF_F_GSO) @@ -2375,13 +2378,14 @@ void sk_setup_caps(struct sock *sk, struct dst_entry *dst) sk->sk_route_caps &= ~NETIF_F_GSO_MASK; } else { sk->sk_route_caps |= NETIF_F_SG | NETIF_F_HW_CSUM; - sk->sk_gso_max_size = sk_dst_gso_max_size(sk, dst); + sk->sk_gso_max_size = sk_dst_gso_max_size(sk, dev); /* pairs with the WRITE_ONCE() in netif_set_gso_max_segs() */ - max_segs = max_t(u32, READ_ONCE(dst_dev(dst)->gso_max_segs), 1); + max_segs = max_t(u32, READ_ONCE(dev->gso_max_segs), 1); } } sk->sk_gso_max_segs = max_segs; sk_dst_set(sk, dst); + rcu_read_unlock(); } EXPORT_SYMBOL_GPL(sk_setup_caps);