Improve and fix the stack-protector tests.
Bug: http://b/26888853
Change-Id: I505dbf7d5934f7247fb639f55dd6a9341df3947b
diff --git a/tests/stack_protector_test.cpp b/tests/stack_protector_test.cpp
index 22285d1..5f5a241 100644
--- a/tests/stack_protector_test.cpp
+++ b/tests/stack_protector_test.cpp
@@ -27,108 +27,83 @@
#include <unistd.h>
#include <set>
-extern "C" pid_t gettid();
+#include "private/bionic_tls.h"
-// For x86, bionic and glibc have per-thread stack guard values (all identical).
-#if defined(__i386__)
-static uint32_t GetGuardFromTls() {
- uint32_t guard;
- asm ("mov %%gs:0x14, %0": "=d" (guard));
- return guard;
-}
+extern "C" pid_t gettid(); // glibc defines this but doesn't declare it anywhere.
+
+#if defined(__BIONIC__)
+extern uintptr_t __stack_chk_guard;
+#endif
struct stack_protector_checker {
std::set<pid_t> tids;
- std::set<uint32_t> guards;
+ std::set<void*> guards;
void Check() {
pid_t tid = gettid();
- uint32_t guard = GetGuardFromTls();
+ void* guard = __get_tls()[TLS_SLOT_STACK_GUARD];
- printf("[thread %d] %%gs:0x14 = 0x%08x\n", tid, guard);
+ printf("[thread %d] TLS stack guard = %p\n", tid, guard);
// Duplicate tid. gettid(2) bug? Seeing this would be very upsetting.
ASSERT_TRUE(tids.find(tid) == tids.end());
- // Uninitialized guard. Our bug. Note this is potentially flaky; we _could_ get
- // four random zero bytes, but it should be vanishingly unlikely.
- ASSERT_NE(guard, 0U);
+ // Uninitialized guard. Our bug. Note this is potentially flaky; we _could_
+ // get four random zero bytes, but it should be vanishingly unlikely.
+ ASSERT_NE(guard, nullptr);
+
+#if defined(__BIONIC__)
+ // bionic always has the global too.
+ ASSERT_EQ(__stack_chk_guard, reinterpret_cast<uintptr_t>(guard));
+#endif
tids.insert(tid);
guards.insert(guard);
}
};
-static void* ThreadGuardHelper(void* arg) {
- stack_protector_checker* checker = reinterpret_cast<stack_protector_checker*>(arg);
- checker->Check();
- return NULL;
-}
-#endif // __i386__
-
TEST(stack_protector, same_guard_per_thread) {
-#if defined(__i386__)
+ // Everyone has the TLS slot set, even if their stack protector
+ // implementation doesn't yet use it.
stack_protector_checker checker;
- size_t thread_count = 10;
- for (size_t i = 0; i < thread_count; ++i) {
+
+ // Check the main thread.
+ ASSERT_EQ(getpid(), gettid()); // We are the main thread, right?
+ checker.Check();
+
+ size_t thread_count = 9;
+ for (size_t i = 1; i < thread_count; ++i) {
pthread_t t;
- ASSERT_EQ(0, pthread_create(&t, NULL, ThreadGuardHelper, &checker));
+ ASSERT_EQ(0, pthread_create(&t, NULL, [](void* arg) -> void* {
+ stack_protector_checker* checker = reinterpret_cast<stack_protector_checker*>(arg);
+ checker->Check();
+ return nullptr;
+ }, &checker));
void* result;
ASSERT_EQ(0, pthread_join(t, &result));
ASSERT_EQ(NULL, result);
}
ASSERT_EQ(thread_count, checker.tids.size());
- // bionic and glibc use the same guard for every thread.
+ // Both bionic and glibc use the same guard for every thread.
ASSERT_EQ(1U, checker.guards.size());
-#else // __i386__
- GTEST_LOG_(INFO) << "This test does nothing.\n";
-#endif // __i386__
}
-// For ARM and MIPS, glibc has a global stack check guard value.
-#if defined(__BIONIC__) || defined(__arm__) || defined(__mips__)
-#define TEST_STACK_CHK_GUARD
-
-// Bionic has the global for x86 too, to support binaries that can run on
-// Android releases that didn't implement the TLS guard value.
-extern "C" uintptr_t __stack_chk_guard;
-
-/*
- * When this function returns, the stack canary will be inconsistent
- * with the previous value, which will generate a call to __stack_chk_fail(),
- * eventually resulting in a SIGABRT.
- *
- * This must be marked with "__attribute__ ((noinline))", to ensure the
- * compiler generates the proper stack guards around this function.
- */
-static char* dummy_buf;
-
-__attribute__ ((noinline))
-static void do_modify_stack_chk_guard() {
- char buf[128];
- // Store local array's address to global variable to force compiler to generate stack guards.
- dummy_buf = buf;
- __stack_chk_guard = 0x12345678;
-}
-
-#endif
-
TEST(stack_protector, global_guard) {
-#if defined(TEST_STACK_CHK_GUARD)
+#if defined(__BIONIC__)
+ // Bionic always has a global, even if it's using TLS.
ASSERT_NE(0, gettid());
ASSERT_NE(0U, __stack_chk_guard);
-#else // TEST_STACK_CHK_GUARD
- GTEST_LOG_(INFO) << "This test does nothing.\n";
-#endif // TEST_STACK_CHK_GUARD
+#else
+ GTEST_LOG_(INFO) << "glibc doesn't have a global __stack_chk_guard.\n";
+#endif
}
class stack_protector_DeathTest : public BionicDeathTest {};
TEST_F(stack_protector_DeathTest, modify_stack_protector) {
-#if defined(TEST_STACK_CHK_GUARD)
- ASSERT_EXIT(do_modify_stack_chk_guard(), testing::KilledBySignal(SIGABRT), "");
-#else // TEST_STACK_CHK_GUARD
- GTEST_LOG_(INFO) << "This test does nothing.\n";
-#endif // TEST_STACK_CHK_GUARD
+ // In another file to prevent inlining, which removes stack protection.
+ extern void modify_stack_protector_test();
+ ASSERT_EXIT(modify_stack_protector_test(),
+ testing::KilledBySignal(SIGABRT), "stack corruption detected");
}