// https://syzkaller.appspot.com/bug?id=4006bcda50967d109d7512134751ca8fb84d393f // autogenerated by syzkaller (https://github.com/google/syzkaller) #define _GNU_SOURCE #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include static __thread int skip_segv; static __thread jmp_buf segv_env; static void segv_handler(int sig, siginfo_t* info, void* ctx) { uintptr_t addr = (uintptr_t)info->si_addr; const uintptr_t prog_start = 1 << 20; const uintptr_t prog_end = 100 << 20; if (__atomic_load_n(&skip_segv, __ATOMIC_RELAXED) && (addr < prog_start || addr > prog_end)) { _longjmp(segv_env, 1); } exit(sig); } static void install_segv_handler(void) { struct sigaction sa; memset(&sa, 0, sizeof(sa)); sa.sa_handler = SIG_IGN; syscall(SYS_rt_sigaction, 0x20, &sa, NULL, 8); syscall(SYS_rt_sigaction, 0x21, &sa, NULL, 8); memset(&sa, 0, sizeof(sa)); sa.sa_sigaction = segv_handler; sa.sa_flags = SA_NODEFER | SA_SIGINFO; sigaction(SIGSEGV, &sa, NULL); sigaction(SIGBUS, &sa, NULL); } #define NONFAILING(...) \ { \ __atomic_fetch_add(&skip_segv, 1, __ATOMIC_SEQ_CST); \ if (_setjmp(segv_env) == 0) { \ __VA_ARGS__; \ } \ __atomic_fetch_sub(&skip_segv, 1, __ATOMIC_SEQ_CST); \ } static void sleep_ms(uint64_t ms) { usleep(ms * 1000); } static uint64_t current_time_ms(void) { struct timespec ts; if (clock_gettime(CLOCK_MONOTONIC, &ts)) exit(1); return (uint64_t)ts.tv_sec * 1000 + (uint64_t)ts.tv_nsec / 1000000; } static void thread_start(void* (*fn)(void*), void* arg) { pthread_t th; pthread_attr_t attr; pthread_attr_init(&attr); pthread_attr_setstacksize(&attr, 128 << 10); int i; for (i = 0; i < 100; i++) { if (pthread_create(&th, &attr, fn, arg) == 0) { pthread_attr_destroy(&attr); return; } if (errno == EAGAIN) { usleep(50); continue; } break; } exit(1); } typedef struct { int state; } event_t; static void event_init(event_t* ev) { ev->state = 0; } static void event_reset(event_t* ev) { ev->state = 0; } static void event_set(event_t* ev) { if (ev->state) exit(1); __atomic_store_n(&ev->state, 1, __ATOMIC_RELEASE); syscall(SYS_futex, &ev->state, FUTEX_WAKE | FUTEX_PRIVATE_FLAG); } static void event_wait(event_t* ev) { while (!__atomic_load_n(&ev->state, __ATOMIC_ACQUIRE)) syscall(SYS_futex, &ev->state, FUTEX_WAIT | FUTEX_PRIVATE_FLAG, 0, 0); } static int event_isset(event_t* ev) { return __atomic_load_n(&ev->state, __ATOMIC_ACQUIRE); } static int event_timedwait(event_t* ev, uint64_t timeout) { uint64_t start = current_time_ms(); uint64_t now = start; for (;;) { uint64_t remain = timeout - (now - start); struct timespec ts; ts.tv_sec = remain / 1000; ts.tv_nsec = (remain % 1000) * 1000 * 1000; syscall(SYS_futex, &ev->state, FUTEX_WAIT | FUTEX_PRIVATE_FLAG, 0, &ts); if (__atomic_load_n(&ev->state, __ATOMIC_RELAXED)) return 1; now = current_time_ms(); if (now - start > timeout) return 0; } } static long syz_open_dev(long a0, long a1, long a2) { if (a0 == 0xc || a0 == 0xb) { char buf[128]; sprintf(buf, "/dev/%s/%d:%d", a0 == 0xc ? "char" : "block", (uint8_t)a1, (uint8_t)a2); return open(buf, O_RDWR, 0); } else { char buf[1024]; char* hash; NONFAILING(strncpy(buf, (char*)a0, sizeof(buf) - 1)); buf[sizeof(buf) - 1] = 0; while ((hash = strchr(buf, '#'))) { *hash = '0' + (char)(a1 % 10); a1 /= 10; } return open(buf, a2, 0); } } struct thread_t { int created, call; event_t ready, done; }; static struct thread_t threads[16]; static void execute_call(int call); static int running; static void* thr(void* arg) { struct thread_t* th = (struct thread_t*)arg; for (;;) { event_wait(&th->ready); event_reset(&th->ready); execute_call(th->call); __atomic_fetch_sub(&running, 1, __ATOMIC_RELAXED); event_set(&th->done); } return 0; } static void loop(void) { int i, call, thread; int collide = 0; again: for (call = 0; call < 5; call++) { for (thread = 0; thread < (int)(sizeof(threads) / sizeof(threads[0])); thread++) { struct thread_t* th = &threads[thread]; if (!th->created) { th->created = 1; event_init(&th->ready); event_init(&th->done); event_set(&th->done); thread_start(thr, th); } if (!event_isset(&th->done)) continue; event_reset(&th->done); th->call = call; __atomic_fetch_add(&running, 1, __ATOMIC_RELAXED); event_set(&th->ready); if (collide && (call % 2) == 0) break; event_timedwait(&th->done, 45); break; } } for (i = 0; i < 100 && __atomic_load_n(&running, __ATOMIC_RELAXED); i++) sleep_ms(1); if (!collide) { collide = 1; goto again; } } #ifndef __NR_ioctl #define __NR_ioctl 54 #endif #ifndef __NR_memfd_create #define __NR_memfd_create 356 #endif #ifndef __NR_mmap #define __NR_mmap 192 #endif #undef __NR_mmap #define __NR_mmap __NR_mmap2 uint64_t r[3] = {0xffffffffffffffff, 0xffffffffffffffff, 0xffffffffffffffff}; void execute_call(int call) { long res; switch (call) { case 0: res = syz_open_dev(0, 0, 0x105082); if (res != -1) r[0] = res; break; case 1: NONFAILING(memcpy((void*)0x20000600, "uservboxnet0vmnet0(mim\345_type]&{ppp1user\000", 40)); res = syscall(__NR_memfd_create, 0x20000600, 2); if (res != -1) r[1] = res; break; case 2: syscall(__NR_ioctl, (long)r[0], 0x4c00, (long)r[1]); break; case 3: NONFAILING(memcpy((void*)0x20000500, "/dev/loop#\000", 11)); res = syz_open_dev(0x20000500, 0, 0); if (res != -1) r[2] = res; break; case 4: NONFAILING(*(uint32_t*)0x20000040 = 0); NONFAILING(*(uint32_t*)0x20000044 = 0); NONFAILING(*(uint32_t*)0x20000048 = 0); NONFAILING(*(uint32_t*)0x2000004c = 0); NONFAILING(*(uint32_t*)0x20000050 = 0); NONFAILING(*(uint32_t*)0x20000054 = 0); NONFAILING(*(uint32_t*)0x20000058 = 0); NONFAILING(*(uint32_t*)0x2000005c = 9); NONFAILING(memcpy((void*)0x20000060, "\x3d\x47\x0b\xae\xfe\x0f\x6c\xaf\x8f\x1f\x9b\x0f\xb2\x5e" "\x47\x70\x8d\x96\x90\xd3\x2e\x6e\xae\x7b\x99\x29\xcd\x01" "\x8c\x64\x7e\xf9\xd4\x33\x5b\x3f\x39\xc1\x95\xd4\x42\x0e" "\x25\xfe\x92\x08\x2e\x19\xf8\x42\xea\xbe\x0d\x37\x2e\x61" "\xd9\xa2\xbb\x2f\x7a\x7b\x7e\xd9", 64)); NONFAILING(memcpy((void*)0x200000a0, "\x22\xb6\x89\xc7\x14\xcc\x1e\x14\x6f" "\xd2\xb3\x88\x25\x5a\xfa\x2f\x7c\x29" "\x25\xa5\xc7\xfb\x93\xbb\xd0\x63\xd0" "\x21\x25\x87\xe1\xf6", 32)); NONFAILING(*(uint32_t*)0x200000c0 = 0); NONFAILING(*(uint32_t*)0x200000c4 = 0); NONFAILING(*(uint32_t*)0x200000c8 = 0); syscall(__NR_ioctl, (long)r[2], 0x4c02, 0x20000040); break; } } int main(void) { syscall(__NR_mmap, 0x20000000, 0x1000000, 3, 0x32, -1, 0); install_segv_handler(); loop(); return 0; }