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Ensure stack usage remains low when unwinding the stack, to prevent stack overflows

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PiperOrigin-RevId: 792704790
Change-Id: I4484219d570e84205cf7da95f71e3c8a00a590e8
This commit is contained in:
Abseil Team
2025-08-08 11:46:00 -07:00
committed by Copybara-Service
parent fd266b9c35
commit 6b15d34113
1 changed files with 50 additions and 0 deletions
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50
absl/debugging/stacktrace_test.cc
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@@ -21,6 +21,7 @@
#include <cerrno>
#include <csignal>
#include <cstring>
#include <memory>
#include "gmock/gmock.h"
#include "gtest/gtest.h"
@@ -32,6 +33,7 @@
static int g_should_fixup_calls = 0;
static int g_fixup_calls = 0;
static bool g_enable_fixup = false;
static uintptr_t g_last_fixup_frame_address = 0;
#if ABSL_HAVE_ATTRIBUTE_WEAK
bool absl::internal_stacktrace::ShouldFixUpStack() {
@@ -41,6 +43,11 @@ bool absl::internal_stacktrace::ShouldFixUpStack() {
void absl::internal_stacktrace::FixUpStack(void**, uintptr_t*, int*, size_t,
size_t&) {
const void* frame_address = nullptr;
#if ABSL_HAVE_BUILTIN(__builtin_frame_address)
frame_address = __builtin_frame_address(0);
#endif
g_last_fixup_frame_address = reinterpret_cast<uintptr_t>(frame_address);
++g_fixup_calls;
}
#endif
@@ -223,6 +230,49 @@ ABSL_ATTRIBUTE_NOINLINE static void FixupNoFixupEquivalenceNoInline() {
TEST(StackTrace, FixupNoFixupEquivalence) { FixupNoFixupEquivalenceNoInline(); }
TEST(StackTrace, FixupLowStackUsage) {
#if !ABSL_HAVE_ATTRIBUTE_WEAK
GTEST_SKIP() << "Skipping test on MSVC due to weak symbols";
#endif
#if defined(_WIN32)
// TODO(b/434184677): Add support for fixups on Windows if needed
GTEST_SKIP() << "Skipping test on Windows due to lack of support for fixups";
#endif
const Cleanup restore_state([enable_fixup = g_enable_fixup,
fixup_calls = g_fixup_calls,
should_fixup_calls = g_should_fixup_calls]() {
g_enable_fixup = enable_fixup;
g_fixup_calls = fixup_calls;
g_should_fixup_calls = should_fixup_calls;
});
g_enable_fixup = true;
// Request a ton of stack frames, regardless of how many are actually used.
// It's fine to request more frames than we have, since functions preallocate
// memory before discovering how high the stack really is, and we're really
// just trying to make sure the preallocations don't overflow the stack.
//
// Note that we loop in order to cover all sides of any branches in the
// implementation that switch allocation behavior (e.g., from stack to heap)
// and to ensure that no sides allocate too much stack space.
constexpr size_t kPageSize = 4096;
for (size_t depth = 2; depth < (1 << 20); depth += depth / 2) {
const auto stack = std::make_unique<void*[]>(depth);
const auto frames = std::make_unique<int[]>(depth);
absl::GetStackFrames(stack.get(), frames.get(), static_cast<int>(depth), 0);
const void* frame_address = nullptr;
#if ABSL_HAVE_BUILTIN(__builtin_frame_address)
frame_address = __builtin_frame_address(0);
#endif
size_t stack_usage =
reinterpret_cast<uintptr_t>(frame_address) - g_last_fixup_frame_address;
EXPECT_LT(stack_usage, kPageSize);
}
}
TEST(StackTrace, CustomUnwinderPerformsFixup) {
#if !ABSL_HAVE_ATTRIBUTE_WEAK
GTEST_SKIP() << "Need weak symbol support";