| /* | 
 |  * Copyright 2006, 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. | 
 |  */ | 
 |  | 
 | #define LOG_TAG "crasher" | 
 |  | 
 | #include <assert.h> | 
 | #include <dirent.h> | 
 | #include <errno.h> | 
 | #include <fcntl.h> | 
 | #include <pthread.h> | 
 | #include <signal.h> | 
 | #include <stdio.h> | 
 | #include <stdlib.h> | 
 | #include <string.h> | 
 | #include <sys/mman.h> | 
 | #include <sys/prctl.h> | 
 | #include <unistd.h> | 
 |  | 
 | // We test both kinds of logging. | 
 | #include <android-base/logging.h> | 
 | #include <log/log.h> | 
 |  | 
 | #include "seccomp_policy.h" | 
 |  | 
 | #if defined(STATIC_CRASHER) | 
 | #include "debuggerd/handler.h" | 
 | #endif | 
 |  | 
 | #if defined(__arm__) | 
 | // See https://www.kernel.org/doc/Documentation/arm/kernel_user_helpers.txt for details. | 
 | #define __kuser_helper_version (*(int32_t*) 0xffff0ffc) | 
 | typedef void * (__kuser_get_tls_t)(void); | 
 | #define __kuser_get_tls (*(__kuser_get_tls_t*) 0xffff0fe0) | 
 | typedef int (__kuser_cmpxchg_t)(int oldval, int newval, volatile int *ptr); | 
 | #define __kuser_cmpxchg (*(__kuser_cmpxchg_t*) 0xffff0fc0) | 
 | typedef void (__kuser_dmb_t)(void); | 
 | #define __kuser_dmb (*(__kuser_dmb_t*) 0xffff0fa0) | 
 | typedef int (__kuser_cmpxchg64_t)(const int64_t*, const int64_t*, volatile int64_t*); | 
 | #define __kuser_cmpxchg64 (*(__kuser_cmpxchg64_t*) 0xffff0f60) | 
 | #endif | 
 |  | 
 | #define noinline __attribute__((__noinline__)) | 
 |  | 
 | // Avoid name mangling so that stacks are more readable. | 
 | extern "C" { | 
 |  | 
 | void crash1(void); | 
 | void crashnostack(void); | 
 |  | 
 | int do_action(const char* arg); | 
 |  | 
 | noinline void maybe_abort() { | 
 |     if (time(0) != 42) { | 
 |         abort(); | 
 |     } | 
 | } | 
 |  | 
 | char* smash_stack_dummy_buf; | 
 | noinline void smash_stack_dummy_function(volatile int* plen) { | 
 |   smash_stack_dummy_buf[*plen] = 0; | 
 | } | 
 |  | 
 | // This must be marked with "__attribute__ ((noinline))", to ensure the | 
 | // compiler generates the proper stack guards around this function. | 
 | // Assign local array address to global variable to force stack guards. | 
 | // Use another noinline function to corrupt the stack. | 
 | noinline int smash_stack(volatile int* plen) { | 
 |     printf("%s: deliberately corrupting stack...\n", getprogname()); | 
 |  | 
 |     char buf[128]; | 
 |     smash_stack_dummy_buf = buf; | 
 |     // This should corrupt stack guards and make process abort. | 
 |     smash_stack_dummy_function(plen); | 
 |     return 0; | 
 | } | 
 |  | 
 | #pragma clang diagnostic push | 
 | #pragma clang diagnostic ignored "-Winfinite-recursion" | 
 |  | 
 | void* global = 0; // So GCC doesn't optimize the tail recursion out of overflow_stack. | 
 |  | 
 | noinline void overflow_stack(void* p) { | 
 |     void* buf[1]; | 
 |     buf[0] = p; | 
 |     global = buf; | 
 |     overflow_stack(&buf); | 
 | } | 
 |  | 
 | #pragma clang diagnostic pop | 
 |  | 
 | noinline void* thread_callback(void* raw_arg) { | 
 |     const char* arg = reinterpret_cast<const char*>(raw_arg); | 
 |     return reinterpret_cast<void*>(static_cast<uintptr_t>(do_action(arg))); | 
 | } | 
 |  | 
 | noinline int do_action_on_thread(const char* arg) { | 
 |     pthread_t t; | 
 |     pthread_create(&t, nullptr, thread_callback, const_cast<char*>(arg)); | 
 |     void* result = nullptr; | 
 |     pthread_join(t, &result); | 
 |     return reinterpret_cast<uintptr_t>(result); | 
 | } | 
 |  | 
 | noinline int crash_null() { | 
 |   int (*null_func)() = nullptr; | 
 |   return null_func(); | 
 | } | 
 |  | 
 | noinline int crash3(int a) { | 
 |     *reinterpret_cast<int*>(0xdead) = a; | 
 |     return a*4; | 
 | } | 
 |  | 
 | noinline int crash2(int a) { | 
 |     a = crash3(a) + 2; | 
 |     return a*3; | 
 | } | 
 |  | 
 | noinline int crash(int a) { | 
 |     a = crash2(a) + 1; | 
 |     return a*2; | 
 | } | 
 |  | 
 | noinline void abuse_heap() { | 
 |     char buf[16]; | 
 |     free(buf); // GCC is smart enough to warn about this, but we're doing it deliberately. | 
 | } | 
 |  | 
 | noinline void leak() { | 
 |     while (true) { | 
 |         void* mapping = | 
 |             mmap(nullptr, PAGE_SIZE, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); | 
 |         static_cast<volatile char*>(mapping)[0] = 'a'; | 
 |     } | 
 | } | 
 |  | 
 | noinline void sigsegv_non_null() { | 
 |     int* a = (int *)(&do_action); | 
 |     *a = 42; | 
 | } | 
 |  | 
 | noinline void fprintf_null() { | 
 |     fprintf(nullptr, "oops"); | 
 | } | 
 |  | 
 | noinline void readdir_null() { | 
 |     readdir(nullptr); | 
 | } | 
 |  | 
 | noinline int strlen_null() { | 
 |     char* sneaky_null = nullptr; | 
 |     return strlen(sneaky_null); | 
 | } | 
 |  | 
 | static int usage() { | 
 |     fprintf(stderr, "usage: %s KIND\n", getprogname()); | 
 |     fprintf(stderr, "\n"); | 
 |     fprintf(stderr, "where KIND is:\n"); | 
 |     fprintf(stderr, "  smash-stack           overwrite a -fstack-protector guard\n"); | 
 |     fprintf(stderr, "  stack-overflow        recurse until the stack overflows\n"); | 
 |     fprintf(stderr, "  nostack               crash with a NULL stack pointer\n"); | 
 |     fprintf(stderr, "\n"); | 
 |     fprintf(stderr, "  heap-usage            cause a libc abort by abusing a heap function\n"); | 
 |     fprintf(stderr, "  call-null             cause a crash by calling through a nullptr\n"); | 
 |     fprintf(stderr, "  leak                  leak memory until we get OOM-killed\n"); | 
 |     fprintf(stderr, "\n"); | 
 |     fprintf(stderr, "  abort                 call abort()\n"); | 
 |     fprintf(stderr, "  assert                call assert() without a function\n"); | 
 |     fprintf(stderr, "  assert2               call assert() with a function\n"); | 
 |     fprintf(stderr, "  exit                  call exit(1)\n"); | 
 |     fprintf(stderr, "\n"); | 
 |     fprintf(stderr, "  fortify               fail a _FORTIFY_SOURCE check\n"); | 
 |     fprintf(stderr, "  seccomp               fail a seccomp check\n"); | 
 | #if defined(__arm__) | 
 |     fprintf(stderr, "  kuser_helper_version  call kuser_helper_version\n"); | 
 |     fprintf(stderr, "  kuser_get_tls         call kuser_get_tls\n"); | 
 |     fprintf(stderr, "  kuser_cmpxchg         call kuser_cmpxchg\n"); | 
 |     fprintf(stderr, "  kuser_memory_barrier  call kuser_memory_barrier\n"); | 
 |     fprintf(stderr, "  kuser_cmpxchg64       call kuser_cmpxchg64\n"); | 
 | #endif | 
 |     fprintf(stderr, "\n"); | 
 |     fprintf(stderr, "  LOG_ALWAYS_FATAL      call liblog LOG_ALWAYS_FATAL\n"); | 
 |     fprintf(stderr, "  LOG_ALWAYS_FATAL_IF   call liblog LOG_ALWAYS_FATAL_IF\n"); | 
 |     fprintf(stderr, "  LOG-FATAL             call libbase LOG(FATAL)\n"); | 
 |     fprintf(stderr, "\n"); | 
 |     fprintf(stderr, "  SIGFPE                cause a SIGFPE\n"); | 
 |     fprintf(stderr, "  SIGSEGV               cause a SIGSEGV at address 0x0 (synonym: crash)\n"); | 
 |     fprintf(stderr, "  SIGSEGV-non-null      cause a SIGSEGV at a non-zero address\n"); | 
 |     fprintf(stderr, "  SIGSEGV-unmapped      mmap/munmap a region of memory and then attempt to access it\n"); | 
 |     fprintf(stderr, "  SIGTRAP               cause a SIGTRAP\n"); | 
 |     fprintf(stderr, "\n"); | 
 |     fprintf(stderr, "  fprintf-NULL          pass a null pointer to fprintf\n"); | 
 |     fprintf(stderr, "  readdir-NULL          pass a null pointer to readdir\n"); | 
 |     fprintf(stderr, "  strlen-NULL           pass a null pointer to strlen\n"); | 
 |     fprintf(stderr, "  pthread_join-NULL     pass a null pointer to pthread_join\n"); | 
 |     fprintf(stderr, "\n"); | 
 |     fprintf(stderr, "  no_new_privs          set PR_SET_NO_NEW_PRIVS and then abort\n"); | 
 |     fprintf(stderr, "\n"); | 
 |     fprintf(stderr, "prefix any of the above with 'thread-' to run on a new thread\n"); | 
 |     fprintf(stderr, "prefix any of the above with 'exhaustfd-' to exhaust\n"); | 
 |     fprintf(stderr, "all available file descriptors before crashing.\n"); | 
 |     fprintf(stderr, "prefix any of the above with 'wait-' to wait until input is received on stdin\n"); | 
 |  | 
 |     return EXIT_FAILURE; | 
 | } | 
 |  | 
 | noinline int do_action(const char* arg) { | 
 |     // Prefixes. | 
 |     if (!strncmp(arg, "wait-", strlen("wait-"))) { | 
 |       char buf[1]; | 
 |       TEMP_FAILURE_RETRY(read(STDIN_FILENO, buf, sizeof(buf))); | 
 |       return do_action(arg + strlen("wait-")); | 
 |     } else if (!strncmp(arg, "exhaustfd-", strlen("exhaustfd-"))) { | 
 |       errno = 0; | 
 |       while (errno != EMFILE) { | 
 |         open("/dev/null", O_RDONLY); | 
 |       } | 
 |       return do_action(arg + strlen("exhaustfd-")); | 
 |     } else if (!strncmp(arg, "thread-", strlen("thread-"))) { | 
 |         return do_action_on_thread(arg + strlen("thread-")); | 
 |     } | 
 |  | 
 |     // Actions. | 
 |     if (!strcasecmp(arg, "SIGSEGV-non-null")) { | 
 |         sigsegv_non_null(); | 
 |     } else if (!strcasecmp(arg, "smash-stack")) { | 
 |         volatile int len = 128; | 
 |         return smash_stack(&len); | 
 |     } else if (!strcasecmp(arg, "stack-overflow")) { | 
 |         overflow_stack(nullptr); | 
 |     } else if (!strcasecmp(arg, "nostack")) { | 
 |         crashnostack(); | 
 |     } else if (!strcasecmp(arg, "exit")) { | 
 |         exit(1); | 
 |     } else if (!strcasecmp(arg, "call-null")) { | 
 |       return crash_null(); | 
 |     } else if (!strcasecmp(arg, "crash") || !strcmp(arg, "SIGSEGV")) { | 
 |         return crash(42); | 
 |     } else if (!strcasecmp(arg, "abort")) { | 
 |         maybe_abort(); | 
 |     } else if (!strcasecmp(arg, "assert")) { | 
 |         __assert("some_file.c", 123, "false"); | 
 |     } else if (!strcasecmp(arg, "assert2")) { | 
 |         __assert2("some_file.c", 123, "some_function", "false"); | 
 |     } else if (!strcasecmp(arg, "fortify")) { | 
 |         char buf[10]; | 
 |         __read_chk(-1, buf, 32, 10); | 
 |         while (true) pause(); | 
 |     } else if (!strcasecmp(arg, "LOG(FATAL)")) { | 
 |         LOG(FATAL) << "hello " << 123; | 
 |     } else if (!strcasecmp(arg, "LOG_ALWAYS_FATAL")) { | 
 |         LOG_ALWAYS_FATAL("hello %s", "world"); | 
 |     } else if (!strcasecmp(arg, "LOG_ALWAYS_FATAL_IF")) { | 
 |         LOG_ALWAYS_FATAL_IF(true, "hello %s", "world"); | 
 |     } else if (!strcasecmp(arg, "SIGFPE")) { | 
 |         raise(SIGFPE); | 
 |         return EXIT_SUCCESS; | 
 |     } else if (!strcasecmp(arg, "SIGTRAP")) { | 
 |         raise(SIGTRAP); | 
 |         return EXIT_SUCCESS; | 
 |     } else if (!strcasecmp(arg, "fprintf-NULL")) { | 
 |         fprintf_null(); | 
 |     } else if (!strcasecmp(arg, "readdir-NULL")) { | 
 |         readdir_null(); | 
 |     } else if (!strcasecmp(arg, "strlen-NULL")) { | 
 |         return strlen_null(); | 
 |     } else if (!strcasecmp(arg, "pthread_join-NULL")) { | 
 |         return pthread_join(0, nullptr); | 
 |     } else if (!strcasecmp(arg, "heap-usage")) { | 
 |         abuse_heap(); | 
 |     } else if (!strcasecmp(arg, "leak")) { | 
 |         leak(); | 
 |     } else if (!strcasecmp(arg, "SIGSEGV-unmapped")) { | 
 |         char* map = reinterpret_cast<char*>(mmap(nullptr, sizeof(int), PROT_READ | PROT_WRITE, | 
 |                                                  MAP_SHARED | MAP_ANONYMOUS, -1, 0)); | 
 |         munmap(map, sizeof(int)); | 
 |         map[0] = '8'; | 
 |     } else if (!strcasecmp(arg, "seccomp")) { | 
 |         set_system_seccomp_filter(); | 
 |         syscall(99999); | 
 | #if defined(__arm__) | 
 |     } else if (!strcasecmp(arg, "kuser_helper_version")) { | 
 |         return __kuser_helper_version; | 
 |     } else if (!strcasecmp(arg, "kuser_get_tls")) { | 
 |         return !__kuser_get_tls(); | 
 |     } else if (!strcasecmp(arg, "kuser_cmpxchg")) { | 
 |         return __kuser_cmpxchg(0, 0, 0); | 
 |     } else if (!strcasecmp(arg, "kuser_memory_barrier")) { | 
 |         __kuser_dmb(); | 
 |     } else if (!strcasecmp(arg, "kuser_cmpxchg64")) { | 
 |         return __kuser_cmpxchg64(0, 0, 0); | 
 | #endif | 
 |     } else if (!strcasecmp(arg, "no_new_privs")) { | 
 |         if (prctl(PR_SET_NO_NEW_PRIVS, 1) != 0) { | 
 |           fprintf(stderr, "prctl(PR_SET_NO_NEW_PRIVS, 1) failed: %s\n", strerror(errno)); | 
 |           return EXIT_SUCCESS; | 
 |         } | 
 |         abort(); | 
 |     } else { | 
 |         return usage(); | 
 |     } | 
 |  | 
 |     fprintf(stderr, "%s: exiting normally!\n", getprogname()); | 
 |     return EXIT_SUCCESS; | 
 | } | 
 |  | 
 | int main(int argc, char** argv) { | 
 | #if defined(STATIC_CRASHER) | 
 |     debuggerd_callbacks_t callbacks = { | 
 |       .get_abort_message = []() { | 
 |         static struct { | 
 |           size_t size; | 
 |           char msg[32]; | 
 |         } msg; | 
 |  | 
 |         msg.size = strlen("dummy abort message"); | 
 |         memcpy(msg.msg, "dummy abort message", strlen("dummy abort message")); | 
 |         return reinterpret_cast<abort_msg_t*>(&msg); | 
 |       }, | 
 |       .post_dump = nullptr | 
 |     }; | 
 |     debuggerd_init(&callbacks); | 
 | #endif | 
 |  | 
 |     if (argc == 1) crash1(); | 
 |     else if (argc == 2) return do_action(argv[1]); | 
 |  | 
 |     return usage(); | 
 | } | 
 |  | 
 | }; |