Ensure stack usage remains low when unwinding the stack, to prevent stack overflows
PiperOrigin-RevId: 792704790
Change-Id: I4484219d570e84205cf7da95f71e3c8a00a590e8
diff --git a/absl/debugging/stacktrace_test.cc b/absl/debugging/stacktrace_test.cc
index e9e9482..4f48a89 100644
--- a/absl/debugging/stacktrace_test.cc
+++ b/absl/debugging/stacktrace_test.cc
@@ -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 @@
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 @@
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";
