| /* |
| * Copyright (C) 2012 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| /* |
| * Contributed by: Intel Corporation |
| */ |
| |
| #include <gtest/gtest.h> |
| |
| #include <pthread.h> |
| #include <stdint.h> |
| #include <stdio.h> |
| #include <sys/syscall.h> |
| #include <unistd.h> |
| #include <set> |
| |
| #ifdef __GLIBC__ |
| |
| // glibc doesn't expose gettid(2). |
| pid_t gettid() { return syscall(__NR_gettid); } |
| |
| #endif |
| |
| #ifdef __i386__ |
| |
| // For x86, bionic and glibc have per-thread stack guard values (all identical). |
| |
| static uint32_t GetGuardFromTls() { |
| uint32_t guard; |
| asm ("mov %%gs:0x14, %0": "=d" (guard)); |
| return guard; |
| } |
| |
| struct stack_protector_checker { |
| std::set<pid_t> tids; |
| std::set<uint32_t> guards; |
| |
| void Check() { |
| pid_t tid = gettid(); |
| uint32_t guard = GetGuardFromTls(); |
| |
| printf("[thread %d] %%gs:0x14 = 0x%08x\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); |
| |
| 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; |
| } |
| |
| TEST(stack_protector, same_guard_per_thread) { |
| stack_protector_checker checker; |
| size_t thread_count = 10; |
| for (size_t i = 0; i < thread_count; ++i) { |
| pthread_t t; |
| ASSERT_EQ(0, pthread_create(&t, NULL, ThreadGuardHelper, &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. |
| ASSERT_EQ(1U, checker.guards.size()); |
| } |
| |
| #endif |
| |
| #if defined(__BIONIC__) || defined(__arm__) || defined(__mips__) |
| |
| // For ARM and MIPS, glibc has a global stack check guard value. |
| |
| // 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; |
| |
| TEST(stack_protector, global_guard) { |
| ASSERT_NE(0, gettid()); |
| ASSERT_NE(0U, __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. |
| */ |
| __attribute__ ((noinline)) |
| static void do_modify_stack_chk_guard() { |
| __stack_chk_guard = 0x12345678; |
| } |
| |
| TEST(stack_protector_DeathTest, modify_stack_protector) { |
| ::testing::FLAGS_gtest_death_test_style = "threadsafe"; |
| ASSERT_EXIT(do_modify_stack_chk_guard(), testing::KilledBySignal(SIGABRT), ""); |
| } |
| |
| #endif |