Fix GWP-ASan metadata race during signal handling, and prevent compiler optimization of dummy allocations in tests.

.bazelrc

@@ -45,11 +45,15 @@ build:asan-libfuzzer --@rules_fuzzing//fuzzing:cc_engine=@rules_fuzzing//fuzzing
 build:asan-libfuzzer --@rules_fuzzing//fuzzing:cc_engine_instrumentation=libfuzzer
 build:asan-libfuzzer --@rules_fuzzing//fuzzing:cc_engine_sanitizer=asan
 
-# Configure our Docker toolchain setup.
-build --extra_toolchains=@docker_toolchain//:all
-build:libstdc++ --features=libstdc++
-build:gcc --platforms=//ci:linux_gcc
-build:clang --platforms=//ci:linux_clang
+# TODO(b/530366451) Replace these with a proper toolchain setup
+build:libstdc++ --repo_env=BAZEL_CXXOPTS= --repo_env=BAZEL_LINKOPTS= --repo_env=CPLUS_INCLUDE_PATH=
+build:libstdc++ --action_env=BAZEL_CXXOPTS= --action_env=BAZEL_LINKOPTS= --action_env=CPLUS_INCLUDE_PATH=
+build:libstdc++ --host_action_env=BAZEL_CXXOPTS= --host_action_env=BAZEL_LINKOPTS= --host_action_env=CPLUS_INCLUDE_PATH=
+
+# TODO(b/530366451) This uses gcc 14, replace with a more recent version.
+build:gcc --config=libstdc++
+build:gcc --host_action_env=CC=/usr/local/bin/gcc --action_env=CC=/usr/bin/gcc
+build:gcc --host_action_env=CXX=/usr/local/bin/g++ --action_env=CXX=/usr/bin/g++
 
 # Remote build configuration for CI.
 build:remote-base --define=EXECUTOR=remote

.github/workflows/ci.yml

@@ -45,7 +45,7 @@ jobs:
     runs-on: ubuntu-24.04
     name: Linux ${{ matrix.toolchain }} ${{ matrix.compilation_mode }} ${{ matrix.exceptions }} Bazel
     container:
-      image: gcr.io/google.com/absl-177019/gloop-linux-toolchain-latest@sha256:a820c79d3f356a64db121a4ee16c4408df18f9d2c8bf6c6abfae21666ac003ba
+      image: gcr.io/google.com/absl-177019/gloop-linux-latest@sha256:903f3d7733dd615bc1542b548fab4b649cf6e48118251a2c6527ce4e30543c6b
       options: --cap-add=SYS_PTRACE
       credentials:
         # TODO(b/530366451) Switch to Workload Identity Federation to avoid the need for secrets and

MODULE.bazel

@@ -38,9 +38,3 @@ bazel_dep(
     version = "20260708.rc1",
     repo_name = "do_not_use_for_gloop_visibility_only",
 )
-
-bazel_dep(name = "docker_toolchain", version = "0.1", dev_dependency = True)
-local_path_override(
-    module_name = "docker_toolchain",
-    path = "ci/docker_toolchain",
-)

ci/BUILD

@@ -1,4 +1,7 @@
-package(default_visibility = ["//visibility:private"])
+package(
+    default_applicable_licenses = ["//tcmalloc:license"],
+    default_visibility = ["//visibility:private"],
+)
 
 platform(
     name = "rbe",
@@ -7,27 +10,9 @@ platform(
         "@platforms//cpu:x86_64",
     ],
     exec_properties = {
-        "container-image": "docker://gcr.io/google.com/absl-177019/gloop-linux-latest@sha256:e199623ad0b61b30d240e8bbddf473f65cb1a11da09462001d83b5066dbd9e98",
+        "container-image": "docker://gcr.io/google.com/absl-177019/gloop-linux-latest@sha256:903f3d7733dd615bc1542b548fab4b649cf6e48118251a2c6527ce4e30543c6b",
         "OSArch": "amd64",
         "dockerRunAsRoot": "true",
         "cache-silo-key": "n2-highmem-8-2026-07-07",
     },
 )
-
-platform(
-    name = "linux_gcc",
-    constraint_values = [
-        "@platforms//os:linux",
-        "@platforms//cpu:x86_64",
-        "@bazel_tools//tools/cpp:gcc",
-    ],
-)
-
-platform(
-    name = "linux_clang",
-    constraint_values = [
-        "@platforms//os:linux",
-        "@platforms//cpu:x86_64",
-        "@bazel_tools//tools/cpp:clang",
-    ],
-)

tcmalloc/guarded_page_allocator.cc

@@ -507,6 +507,7 @@ bool GuardedPageAllocator::WriteOverflowOccurred(size_t slot) const {
 GuardedAllocationsErrorType GuardedPageAllocator::GetErrorType(
     uintptr_t addr, const SlotMetadata& d) const {
   if (!d.allocation_start) return GuardedAllocationsErrorType::kUnknown;
+
   size_t dealloc_count = d.dealloc_count.load(std::memory_order_relaxed);
   if (dealloc_count >= 2) return GuardedAllocationsErrorType::kDoubleFree;
   if (d.write_overflow_detected)
@@ -520,7 +521,7 @@ GuardedAllocationsErrorType GuardedPageAllocator::GetErrorType(
   if (addr >= d.allocation_start + d.requested_size) {
     return GuardedAllocationsErrorType::kBufferOverflow;
   }
-  return GuardedAllocationsErrorType::kUnknown;
+  return GuardedAllocationsErrorType::kUseAfterFree;
 }
 
 uintptr_t GuardedPageAllocator::SlotToAddr(size_t slot) const {

tcmalloc/testing/testutil.h

@@ -95,12 +95,14 @@ class ScopedProfileSamplingInterval {
     // Reset the per-thread sampler.  It may have a very large gap if sampling
     // had been disabled.
     void* ptr = ::operator new(256 * 1024 * 1024);
+    benchmark::DoNotOptimize(ptr);
     ::operator delete(ptr);
   }
 
   ~ScopedProfileSamplingInterval() {
     MallocExtension::SetProfileSamplingInterval(previous_);
     void* ptr = ::operator new(256 * 1024 * 1024);
+    benchmark::DoNotOptimize(ptr);
     ::operator delete(ptr);
   }