1 files changed, 117 insertions, 0 deletions
diff --git a/tests/stack_protector_test.cpp b/tests/stack_protector_test.cpp
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+/*
+ * 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.
+
+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());
+#ifdef __GLIBC__
+    // glibc uses the same guard for every thread. bionic uses a different guard for each one.
+#else
+    // Duplicate guard. Our bug. Note this is potentially flaky; we _could_ get the
+    // same guard for two threads, but it should be vanishingly unlikely.
+    ASSERT_TRUE(guards.find(guard) == guards.end());
+#endif
+    // 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, 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());
+
+  // glibc uses the same guard for every thread. bionic uses a different guard for each one.
+#ifdef __BIONIC__
+  ASSERT_EQ(thread_count, checker.guards.size());
+#else
+  ASSERT_EQ(1U, checker.guards.size());
+#endif
+}
+
+#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" void* __stack_chk_guard;
+
+TEST(stack_protector, global_guard) {
+  ASSERT_NE(0, gettid());
+  ASSERT_NE(0U, reinterpret_cast<uintptr_t>(__stack_chk_guard));
+}
+
+#endif