// https://syzkaller.appspot.com/bug?id=b8408774e9a8138e4a0dadca9adc6ac4ff266f17 // 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 #include #include #include #include static bool write_file(const char* file, const char* what, ...) { char buf[1024]; va_list args; va_start(args, what); vsnprintf(buf, sizeof(buf), what, args); va_end(args); buf[sizeof(buf) - 1] = 0; int len = strlen(buf); int fd = open(file, O_WRONLY | O_CLOEXEC); if (fd == -1) return false; if (write(fd, buf, len) != len) { int err = errno; close(fd); errno = err; return false; } close(fd); return true; } static void setup_common() { if (mount(0, "/sys/fs/fuse/connections", "fusectl", 0, 0)) { } } static void loop(); static void sandbox_common() { prctl(PR_SET_PDEATHSIG, SIGKILL, 0, 0, 0); setpgrp(); setsid(); struct rlimit rlim; rlim.rlim_cur = rlim.rlim_max = (200 << 20); setrlimit(RLIMIT_AS, &rlim); rlim.rlim_cur = rlim.rlim_max = 32 << 20; setrlimit(RLIMIT_MEMLOCK, &rlim); rlim.rlim_cur = rlim.rlim_max = 136 << 20; setrlimit(RLIMIT_FSIZE, &rlim); rlim.rlim_cur = rlim.rlim_max = 1 << 20; setrlimit(RLIMIT_STACK, &rlim); rlim.rlim_cur = rlim.rlim_max = 0; setrlimit(RLIMIT_CORE, &rlim); rlim.rlim_cur = rlim.rlim_max = 256; setrlimit(RLIMIT_NOFILE, &rlim); if (unshare(CLONE_NEWNS)) { } if (unshare(CLONE_NEWIPC)) { } if (unshare(0x02000000)) { } if (unshare(CLONE_NEWUTS)) { } if (unshare(CLONE_SYSVSEM)) { } typedef struct { const char* name; const char* value; } sysctl_t; static const sysctl_t sysctls[] = { {"/proc/sys/kernel/shmmax", "16777216"}, {"/proc/sys/kernel/shmall", "536870912"}, {"/proc/sys/kernel/shmmni", "1024"}, {"/proc/sys/kernel/msgmax", "8192"}, {"/proc/sys/kernel/msgmni", "1024"}, {"/proc/sys/kernel/msgmnb", "1024"}, {"/proc/sys/kernel/sem", "1024 1048576 500 1024"}, }; unsigned i; for (i = 0; i < sizeof(sysctls) / sizeof(sysctls[0]); i++) write_file(sysctls[i].name, sysctls[i].value); } static int wait_for_loop(int pid) { if (pid < 0) exit(1); int status = 0; while (waitpid(-1, &status, __WALL) != pid) { } return WEXITSTATUS(status); } static void drop_caps(void) { struct __user_cap_header_struct cap_hdr = {}; struct __user_cap_data_struct cap_data[2] = {}; cap_hdr.version = _LINUX_CAPABILITY_VERSION_3; cap_hdr.pid = getpid(); if (syscall(SYS_capget, &cap_hdr, &cap_data)) exit(1); const int drop = (1 << CAP_SYS_PTRACE) | (1 << CAP_SYS_NICE); cap_data[0].effective &= ~drop; cap_data[0].permitted &= ~drop; cap_data[0].inheritable &= ~drop; if (syscall(SYS_capset, &cap_hdr, &cap_data)) exit(1); } static int do_sandbox_none(void) { if (unshare(CLONE_NEWPID)) { } int pid = fork(); if (pid != 0) return wait_for_loop(pid); setup_common(); sandbox_common(); drop_caps(); if (unshare(CLONE_NEWNET)) { } loop(); exit(1); } uint64_t r[2] = {0xffffffffffffffff, 0xffffffffffffffff}; void loop(void) { intptr_t res = 0; res = syscall(__NR_fcntl, -1, 0ul, -1); if (res != -1) r[0] = res; syscall(__NR_ioctl, r[0], 0x8912, 0x400200ul); memcpy((void*)0x20000180, "/dev/fb0\000", 9); res = syscall(__NR_openat, 0xffffffffffffff9cul, 0x20000180ul, 0ul, 0ul); if (res != -1) r[1] = res; *(uint32_t*)0x200001c0 = 0x40; *(uint32_t*)0x200001c4 = 0; *(uint32_t*)0x200001c8 = 0; *(uint32_t*)0x200001cc = 0x960; *(uint32_t*)0x200001d0 = 0; *(uint32_t*)0x200001d4 = 0; *(uint32_t*)0x200001d8 = 4; *(uint32_t*)0x200001dc = 0; *(uint32_t*)0x200001e0 = 0; *(uint32_t*)0x200001e4 = 0; *(uint32_t*)0x200001e8 = 0; *(uint32_t*)0x200001ec = 0; *(uint32_t*)0x200001f0 = 0; *(uint32_t*)0x200001f4 = 0; *(uint32_t*)0x200001f8 = 0; *(uint32_t*)0x200001fc = 0; *(uint32_t*)0x20000200 = 0; *(uint32_t*)0x20000204 = 0; *(uint32_t*)0x20000208 = 0; *(uint32_t*)0x2000020c = 0; *(uint32_t*)0x20000210 = 2; *(uint32_t*)0x20000214 = 0; *(uint32_t*)0x20000218 = 0; *(uint32_t*)0x2000021c = 0; *(uint32_t*)0x20000220 = 0; *(uint32_t*)0x20000224 = 0; *(uint32_t*)0x20000228 = 0; *(uint32_t*)0x2000022c = 0; *(uint32_t*)0x20000230 = 0; *(uint32_t*)0x20000234 = 0; *(uint32_t*)0x20000238 = 0; *(uint32_t*)0x2000023c = 0; *(uint32_t*)0x20000240 = 0; *(uint32_t*)0x20000244 = 0; *(uint32_t*)0x20000248 = 0; *(uint32_t*)0x2000024c = 0; *(uint32_t*)0x20000250 = 0; *(uint32_t*)0x20000254 = 0; *(uint32_t*)0x20000258 = 0; *(uint32_t*)0x2000025c = 0; syscall(__NR_ioctl, r[1], 0x4601, 0x200001c0ul); } int main(void) { syscall(__NR_mmap, 0x1ffff000ul, 0x1000ul, 0ul, 0x32ul, -1, 0ul); syscall(__NR_mmap, 0x20000000ul, 0x1000000ul, 7ul, 0x32ul, -1, 0ul); syscall(__NR_mmap, 0x21000000ul, 0x1000ul, 0ul, 0x32ul, -1, 0ul); do_sandbox_none(); return 0; }