/*
* 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 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 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-corruption cause a libc abort by corrupting the heap\n");
fprintf(stderr, " heap-usage cause a libc abort by abusing a heap function\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, "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, "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_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();
}
};