ad88a08631
Based on a pair of patches from Intel: https://android-review.googlesource.com/#/c/43909/ https://android-review.googlesource.com/#/c/44903/ For x86, this patch supports _both_ the global that ARM/MIPS use and the per-thread TLS entry (%gs:20) that GCC uses by default. This lets us support binaries built with any x86 toolchain (right now, the NDK is emitting x86 code that uses the global). I've also extended the original tests to cover ARM/MIPS too, and be a little more thorough for x86. Change-Id: I02f279a80c6b626aecad449771dec91df235ad01
118 lines
3.2 KiB
C++
118 lines
3.2 KiB
C++
/*
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* Copyright (C) 2012 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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/*
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* Contributed by: Intel Corporation
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*/
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#include <gtest/gtest.h>
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#include <pthread.h>
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#include <stdint.h>
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#include <stdio.h>
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#include <sys/syscall.h>
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#include <unistd.h>
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#include <set>
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#ifdef __GLIBC__
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// glibc doesn't expose gettid(2).
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pid_t gettid() { return syscall(__NR_gettid); }
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#endif
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#ifdef __i386__
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// For x86, bionic and glibc have per-thread stack guard values.
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static uint32_t GetGuardFromTls() {
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uint32_t guard;
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asm ("mov %%gs:0x14, %0": "=d" (guard));
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return guard;
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}
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struct stack_protector_checker {
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std::set<pid_t> tids;
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std::set<uint32_t> guards;
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void Check() {
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pid_t tid = gettid();
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uint32_t guard = GetGuardFromTls();
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printf("[thread %d] %%gs:0x14 = 0x%08x\n", tid, guard);
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// Duplicate tid. gettid(2) bug? Seeing this would be very upsetting.
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ASSERT_TRUE(tids.find(tid) == tids.end());
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#ifdef __GLIBC__
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// glibc uses the same guard for every thread. bionic uses a different guard for each one.
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#else
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// Duplicate guard. Our bug. Note this is potentially flaky; we _could_ get the
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// same guard for two threads, but it should be vanishingly unlikely.
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ASSERT_TRUE(guards.find(guard) == guards.end());
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#endif
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// Uninitialized guard. Our bug. Note this is potentially flaky; we _could_ get
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// four random zero bytes, but it should be vanishingly unlikely.
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ASSERT_NE(guard, 0U);
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tids.insert(tid);
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guards.insert(guard);
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}
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};
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static void* ThreadGuardHelper(void* arg) {
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stack_protector_checker* checker = reinterpret_cast<stack_protector_checker*>(arg);
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checker->Check();
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return NULL;
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}
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TEST(stack_protector, guard_per_thread) {
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stack_protector_checker checker;
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size_t thread_count = 10;
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for (size_t i = 0; i < thread_count; ++i) {
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pthread_t t;
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ASSERT_EQ(0, pthread_create(&t, NULL, ThreadGuardHelper, &checker));
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void* result;
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ASSERT_EQ(0, pthread_join(t, &result));
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ASSERT_EQ(NULL, result);
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}
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ASSERT_EQ(thread_count, checker.tids.size());
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// glibc uses the same guard for every thread. bionic uses a different guard for each one.
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#ifdef __BIONIC__
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ASSERT_EQ(thread_count, checker.guards.size());
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#else
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ASSERT_EQ(1U, checker.guards.size());
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#endif
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}
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#endif
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#if defined(__BIONIC__) || defined(__arm__) || defined(__mips__)
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// For ARM and MIPS, glibc has a global stack check guard value.
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// Bionic has the global for x86 too, to support binaries that can run on
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// Android releases that didn't implement the TLS guard value.
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extern "C" void* __stack_chk_guard;
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TEST(stack_protector, global_guard) {
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ASSERT_NE(0, gettid());
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ASSERT_NE(0U, reinterpret_cast<uintptr_t>(__stack_chk_guard));
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}
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#endif
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