GH-55445: [C++] Prevent null pointer arithmetic in Buffer and MutableBuffer slicing

cpp/src/arrow/buffer.cc

@@ -164,7 +164,9 @@ std::shared_ptr<Buffer> SliceMutableBuffer(std::shared_ptr<Buffer> buffer,
 
 MutableBuffer::MutableBuffer(const std::shared_ptr<Buffer>& parent, const int64_t offset,
                              const int64_t size)
-    : MutableBuffer(reinterpret_cast<uint8_t*>(parent->mutable_address()) + offset,
+    : MutableBuffer(parent->mutable_address()
+                        ? reinterpret_cast<uint8_t*>(parent->mutable_address() + offset)
+                        : nullptr,
                     size) {
   DCHECK(parent->is_mutable()) << "Must pass mutable buffer";
   parent_ = parent;

cpp/src/arrow/buffer.h

@@ -122,7 +122,7 @@ class ARROW_EXPORT Buffer {
   /// in general we expected buffers to be aligned and padded to 64 bytes.  In the future
   /// we might add utility methods to help determine if a buffer satisfies this contract.
   Buffer(std::shared_ptr<Buffer> parent, const int64_t offset, const int64_t size)
-      : Buffer(parent->data_ + offset, size) {
+      : Buffer(parent->data_ ? parent->data_ + offset : nullptr, size) {
     parent_ = std::move(parent);
     SetMemoryManager(parent_->memory_manager_);
   }

cpp/src/arrow/buffer_test.cc

@@ -516,6 +516,18 @@ TEST(TestBuffer, ToHexString) {
   ASSERT_EQ(buf.ToHexString(), std::string("073068657820737472696E67A9"));
 }
 
+TEST(TestBuffer, SliceNullBuffer) {
+  auto null_buffer = std::make_shared<Buffer>(nullptr, 16);
+  auto sliced = SliceBuffer(null_buffer, 8, 8);
+  EXPECT_EQ(sliced->data(), nullptr);
+  EXPECT_EQ(sliced->size(), 8);
+
+  auto null_mutable = std::make_shared<MutableBuffer>(nullptr, 16);
+  auto sliced_mutable = SliceMutableBuffer(null_mutable, 8, 8);
+  EXPECT_EQ(sliced_mutable->mutable_data(), nullptr);
+  EXPECT_EQ(sliced_mutable->size(), 8);
+}
+
 TEST(TestBuffer, SliceBuffer) {
   std::string data_str = "some data to slice";
   auto data = reinterpret_cast<const uint8_t*>(data_str.c_str());