/* * 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(); } };