// https://syzkaller.appspot.com/bug?id=87ff3bc3ad02b968e5449c39c496d41cd5ceb6b9 // 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 #include #include #include #include #include #include static unsigned long long procid; static __thread int clone_ongoing; static __thread int skip_segv; static __thread jmp_buf segv_env; static void segv_handler(int sig, siginfo_t* info, void* ctx) { if (__atomic_load_n(&clone_ongoing, __ATOMIC_RELAXED) != 0) { exit(sig); } uintptr_t addr = (uintptr_t)info->si_addr; const uintptr_t prog_start = 1 << 20; const uintptr_t prog_end = 100 << 20; int skip = __atomic_load_n(&skip_segv, __ATOMIC_RELAXED) != 0; int valid = addr < prog_start || addr > prog_end; if (skip && valid) { _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(...) \ ({ \ int ok = 1; \ __atomic_fetch_add(&skip_segv, 1, __ATOMIC_SEQ_CST); \ if (_setjmp(segv_env) == 0) { \ __VA_ARGS__; \ } else \ ok = 0; \ __atomic_fetch_sub(&skip_segv, 1, __ATOMIC_SEQ_CST); \ ok; \ }) 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 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 int runcmdline(char* cmdline) { int ret = system(cmdline); if (ret) { } return ret; } #define MAX_FDS 30 static void setup_gadgetfs(); static void setup_binderfs(); static void setup_fusectl(); static void sandbox_common_mount_tmpfs(void) { write_file("/proc/sys/fs/mount-max", "100000"); if (mkdir("./syz-tmp", 0777)) exit(1); if (mount("", "./syz-tmp", "tmpfs", 0, NULL)) exit(1); if (mkdir("./syz-tmp/newroot", 0777)) exit(1); if (mkdir("./syz-tmp/newroot/dev", 0700)) exit(1); unsigned bind_mount_flags = MS_BIND | MS_REC | MS_PRIVATE; if (mount("/dev", "./syz-tmp/newroot/dev", NULL, bind_mount_flags, NULL)) exit(1); if (mkdir("./syz-tmp/newroot/proc", 0700)) exit(1); if (mount("syz-proc", "./syz-tmp/newroot/proc", "proc", 0, NULL)) exit(1); if (mkdir("./syz-tmp/newroot/selinux", 0700)) exit(1); const char* selinux_path = "./syz-tmp/newroot/selinux"; if (mount("/selinux", selinux_path, NULL, bind_mount_flags, NULL)) { if (errno != ENOENT) exit(1); if (mount("/sys/fs/selinux", selinux_path, NULL, bind_mount_flags, NULL) && errno != ENOENT) exit(1); } if (mkdir("./syz-tmp/newroot/sys", 0700)) exit(1); if (mount("/sys", "./syz-tmp/newroot/sys", 0, bind_mount_flags, NULL)) exit(1); if (mount("/sys/kernel/debug", "./syz-tmp/newroot/sys/kernel/debug", NULL, bind_mount_flags, NULL) && errno != ENOENT) exit(1); if (mount("/sys/fs/smackfs", "./syz-tmp/newroot/sys/fs/smackfs", NULL, bind_mount_flags, NULL) && errno != ENOENT) exit(1); if (mount("/proc/sys/fs/binfmt_misc", "./syz-tmp/newroot/proc/sys/fs/binfmt_misc", NULL, bind_mount_flags, NULL) && errno != ENOENT) exit(1); if (mkdir("./syz-tmp/newroot/syz-inputs", 0700)) exit(1); if (mount("/syz-inputs", "./syz-tmp/newroot/syz-inputs", NULL, bind_mount_flags | MS_RDONLY, NULL) && errno != ENOENT) exit(1); if (mkdir("./syz-tmp/pivot", 0777)) exit(1); if (syscall(SYS_pivot_root, "./syz-tmp", "./syz-tmp/pivot")) { if (chdir("./syz-tmp")) exit(1); } else { if (chdir("/")) exit(1); if (umount2("./pivot", MNT_DETACH)) exit(1); } if (chroot("./newroot")) exit(1); if (chdir("/")) exit(1); setup_gadgetfs(); setup_binderfs(); setup_fusectl(); } static void setup_gadgetfs() { if (mkdir("/dev/gadgetfs", 0777)) { } if (mount("gadgetfs", "/dev/gadgetfs", "gadgetfs", 0, NULL)) { } } static void setup_fusectl() { if (mount(0, "/sys/fs/fuse/connections", "fusectl", 0, 0)) { } } static void setup_binderfs() { if (mkdir("/dev/binderfs", 0777)) { } if (mount("binder", "/dev/binderfs", "binder", 0, NULL)) { } if (symlink("/dev/binderfs", "./binderfs")) { } } static void loop(); static void sandbox_common() { prctl(PR_SET_PDEATHSIG, SIGKILL, 0, 0, 0); if (getppid() == 1) exit(1); 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 = 128 << 20; setrlimit(RLIMIT_CORE, &rlim); rlim.rlim_cur = rlim.rlim_max = 256; setrlimit(RLIMIT_NOFILE, &rlim); if (unshare(CLONE_NEWNS)) { } if (mount(NULL, "/", NULL, MS_REC | MS_PRIVATE, NULL)) { } 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); sandbox_common(); drop_caps(); if (unshare(CLONE_NEWNET)) { } write_file("/proc/sys/net/ipv4/ping_group_range", "0 65535"); sandbox_common_mount_tmpfs(); loop(); exit(1); } static void kill_and_wait(int pid, int* status) { kill(-pid, SIGKILL); kill(pid, SIGKILL); for (int i = 0; i < 100; i++) { if (waitpid(-1, status, WNOHANG | __WALL) == pid) return; usleep(1000); } DIR* dir = opendir("/sys/fs/fuse/connections"); if (dir) { for (;;) { struct dirent* ent = readdir(dir); if (!ent) break; if (strcmp(ent->d_name, ".") == 0 || strcmp(ent->d_name, "..") == 0) continue; char abort[300]; snprintf(abort, sizeof(abort), "/sys/fs/fuse/connections/%s/abort", ent->d_name); int fd = open(abort, O_WRONLY); if (fd == -1) { continue; } if (write(fd, abort, 1) < 0) { } close(fd); } closedir(dir); } else { } while (waitpid(-1, status, __WALL) != pid) { } } static void setup_test() { prctl(PR_SET_PDEATHSIG, SIGKILL, 0, 0, 0); setpgrp(); write_file("/proc/self/oom_score_adj", "1000"); } static void close_fds() { for (int fd = 3; fd < MAX_FDS; fd++) close(fd); } static const char* setup_binfmt_misc() { if (mount(0, "/proc/sys/fs/binfmt_misc", "binfmt_misc", 0, 0) && errno != EBUSY) { return NULL; } if (!write_file("/proc/sys/fs/binfmt_misc/register", ":syz0:M:0:\x01::./file0:") || !write_file("/proc/sys/fs/binfmt_misc/register", ":syz1:M:1:\x02::./file0:POC")) return "write(/proc/sys/fs/binfmt_misc/register) failed"; return NULL; } static void setup_sysctl() { int cad_pid = fork(); if (cad_pid < 0) exit(1); if (cad_pid == 0) { for (;;) sleep(100); } char tmppid[32]; snprintf(tmppid, sizeof(tmppid), "%d", cad_pid); struct { const char* name; const char* data; } files[] = { {"/sys/kernel/debug/x86/nmi_longest_ns", "10000000000"}, {"/proc/sys/kernel/hung_task_check_interval_secs", "20"}, {"/proc/sys/net/core/bpf_jit_kallsyms", "1"}, {"/proc/sys/net/core/bpf_jit_harden", "0"}, {"/proc/sys/kernel/kptr_restrict", "0"}, {"/proc/sys/kernel/softlockup_all_cpu_backtrace", "1"}, {"/proc/sys/fs/mount-max", "100"}, {"/proc/sys/vm/oom_dump_tasks", "0"}, {"/proc/sys/debug/exception-trace", "0"}, {"/proc/sys/kernel/printk", "7 4 1 3"}, {"/proc/sys/kernel/keys/gc_delay", "1"}, {"/proc/sys/vm/oom_kill_allocating_task", "1"}, {"/proc/sys/kernel/ctrl-alt-del", "0"}, {"/proc/sys/kernel/cad_pid", tmppid}, }; for (size_t i = 0; i < sizeof(files) / sizeof(files[0]); i++) { if (!write_file(files[i].name, files[i].data)) { } } kill(cad_pid, SIGKILL); while (waitpid(cad_pid, NULL, 0) != cad_pid) ; } #define SWAP_FILE "./swap-file" #define SWAP_FILE_SIZE (128 * 1000 * 1000) static const char* setup_swap() { swapoff(SWAP_FILE); unlink(SWAP_FILE); int fd = open(SWAP_FILE, O_CREAT | O_WRONLY | O_CLOEXEC, 0600); if (fd == -1) return "swap file open failed"; fallocate(fd, FALLOC_FL_ZERO_RANGE, 0, SWAP_FILE_SIZE); close(fd); char cmdline[64]; sprintf(cmdline, "mkswap %s", SWAP_FILE); if (runcmdline(cmdline)) return "mkswap failed"; if (swapon(SWAP_FILE, SWAP_FLAG_PREFER) == 1) return "swapon failed"; return NULL; } static void execute_one(void); #define WAIT_FLAGS __WALL static void loop(void) { int iter = 0; for (;; iter++) { int pid = fork(); if (pid < 0) exit(1); if (pid == 0) { setup_test(); execute_one(); close_fds(); exit(0); } int status = 0; uint64_t start = current_time_ms(); for (;;) { sleep_ms(10); if (waitpid(-1, &status, WNOHANG | WAIT_FLAGS) == pid) break; if (current_time_ms() - start < 5000) continue; kill_and_wait(pid, &status); break; } } } uint64_t r[3] = {0xffffffffffffffff, 0xffffffffffffffff, 0xffffffffffffffff}; void execute_one(void) { intptr_t res = 0; if (write(1, "executing program\n", sizeof("executing program\n") - 1)) { } // openat$kvm arguments: [ // fd: const = 0xffffff9c (8 bytes) // file: ptr[in, buffer] { // buffer: {2f 64 65 76 2f 6b 76 6d 00} (length 0x9) // } // flags: open_flags = 0x41 (4 bytes) // mode: const = 0x0 (2 bytes) // ] // returns fd_kvm NONFAILING(memcpy((void*)0x200000000100, "/dev/kvm\000", 9)); res = syscall(__NR_openat, /*fd=*/0xffffff9cul, /*file=*/0x200000000100ul, /*flags=O_CREAT|O_WRONLY*/ 0x41, /*mode=*/0); if (res != -1) r[0] = res; // ioctl$KVM_CREATE_VM arguments: [ // fd: fd_kvm (resource) // cmd: const = 0xae01 (4 bytes) // type: intptr = 0x0 (8 bytes) // ] // returns fd_kvmvm res = syscall(__NR_ioctl, /*fd=*/r[0], /*cmd=*/0xae01, /*type=*/0ul); if (res != -1) r[1] = res; // ioctl$KVM_CREATE_VCPU arguments: [ // fd: fd_kvmvm (resource) // cmd: const = 0xae41 (4 bytes) // id: intptr = 0x0 (8 bytes) // ] // returns fd_kvmcpu res = syscall(__NR_ioctl, /*fd=*/r[1], /*cmd=*/0xae41, /*id=*/0ul); if (res != -1) r[2] = res; // ioctl$KVM_SET_REGS arguments: [ // fd: fd_kvmcpu (resource) // cmd: const = 0x4090ae82 (4 bytes) // arg: ptr[in, kvm_regs] { // kvm_regs { // gp: array[int64] { // int64 = 0xf (8 bytes) // int64 = 0x3 (8 bytes) // int64 = 0xfffffffffffff602 (8 bytes) // int64 = 0x1000000000000002 (8 bytes) // int64 = 0x5 (8 bytes) // int64 = 0x8000000d (8 bytes) // int64 = 0x9e (8 bytes) // int64 = 0x5 (8 bytes) // int64 = 0x3 (8 bytes) // int64 = 0xffffffff (8 bytes) // int64 = 0xffffffffffffffff (8 bytes) // int64 = 0x1 (8 bytes) // int64 = 0x400000000000d0f (8 bytes) // int64 = 0x4 (8 bytes) // int64 = 0x2000000000000003 (8 bytes) // int64 = 0x800005 (8 bytes) // } // rip: kvm_guest_addrs = 0x80a0000 (8 bytes) // rflags: kvm_x86_rflags = 0x104204 (8 bytes) // } // } // ] NONFAILING(*(uint64_t*)0x200000000600 = 0xf); NONFAILING(*(uint64_t*)0x200000000608 = 3); NONFAILING(*(uint64_t*)0x200000000610 = 0xfffffffffffff602); NONFAILING(*(uint64_t*)0x200000000618 = 0x1000000000000002); NONFAILING(*(uint64_t*)0x200000000620 = 5); NONFAILING(*(uint64_t*)0x200000000628 = 0x8000000d); NONFAILING(*(uint64_t*)0x200000000630 = 0x9e); NONFAILING(*(uint64_t*)0x200000000638 = 5); NONFAILING(*(uint64_t*)0x200000000640 = 3); NONFAILING(*(uint64_t*)0x200000000648 = 0xffffffff); NONFAILING(*(uint64_t*)0x200000000650 = -1); NONFAILING(*(uint64_t*)0x200000000658 = 1); NONFAILING(*(uint64_t*)0x200000000660 = 0x400000000000d0f); NONFAILING(*(uint64_t*)0x200000000668 = 4); NONFAILING(*(uint64_t*)0x200000000670 = 0x2000000000000003); NONFAILING(*(uint64_t*)0x200000000678 = 0x800005); NONFAILING(*(uint64_t*)0x200000000680 = 0x80a0000); NONFAILING(*(uint64_t*)0x200000000688 = 0x104204); syscall(__NR_ioctl, /*fd=*/r[2], /*cmd=*/0x4090ae82, /*arg=*/0x200000000600ul); // ioctl$KVM_RUN arguments: [ // fd: fd_kvmcpu (resource) // cmd: const = 0xae80 (4 bytes) // arg: const = 0x0 (8 bytes) // ] syscall(__NR_ioctl, /*fd=*/r[2], /*cmd=*/0xae80, /*arg=*/0ul); // socket$packet arguments: [ // domain: const = 0x11 (8 bytes) // type: packet_socket_type = 0x3 (8 bytes) // proto: const = 0x300 (4 bytes) // ] // returns sock_packet syscall(__NR_socket, /*domain=*/0x11ul, /*type=SOCK_RAW*/ 3ul, /*proto=*/0x300); // prlimit64 arguments: [ // pid: pid (resource) // res: rlimit_type = 0xe (8 bytes) // new: ptr[in, rlimit] { // rlimit { // soft: intptr = 0x8 (8 bytes) // hard: intptr = 0x8a (8 bytes) // } // } // old: nil // ] NONFAILING(*(uint64_t*)0x200000000200 = 8); NONFAILING(*(uint64_t*)0x200000000208 = 0x8a); syscall(__NR_prlimit64, /*pid=*/0, /*res=RLIMIT_RTPRIO*/ 0xeul, /*new=*/0x200000000200ul, /*old=*/0ul); // sched_setscheduler arguments: [ // pid: pid (resource) // policy: sched_policy = 0x2 (8 bytes) // prio: ptr[in, int32] { // int32 = 0x2 (4 bytes) // } // ] NONFAILING(*(uint32_t*)0x200000000640 = 2); syscall(__NR_sched_setscheduler, /*pid=*/0, /*policy=SCHED_RR*/ 2ul, /*prio=*/0x200000000640ul); // prctl$PR_SCHED_CORE arguments: [ // option: const = 0x3e (8 bytes) // cmd: intptr = 0x1 (8 bytes) // pid: pid (resource) // type: pid_type = 0x1 (8 bytes) // uaddr: nil // ] syscall(__NR_prctl, /*option=*/0x3eul, /*cmd=*/1ul, /*pid=*/0, /*type=PIDTYPE_TGID*/ 1ul, /*uaddr=*/0ul); // ioctl$KVM_RUN arguments: [ // fd: fd_kvmcpu (resource) // cmd: const = 0xae80 (4 bytes) // arg: const = 0x0 (8 bytes) // ] syscall(__NR_ioctl, /*fd=*/r[2], /*cmd=*/0xae80, /*arg=*/0ul); } int main(void) { syscall(__NR_mmap, /*addr=*/0x1ffffffff000ul, /*len=*/0x1000ul, /*prot=*/0ul, /*flags=MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE*/ 0x32ul, /*fd=*/(intptr_t)-1, /*offset=*/0ul); syscall(__NR_mmap, /*addr=*/0x200000000000ul, /*len=*/0x1000000ul, /*prot=PROT_WRITE|PROT_READ|PROT_EXEC*/ 7ul, /*flags=MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE*/ 0x32ul, /*fd=*/(intptr_t)-1, /*offset=*/0ul); syscall(__NR_mmap, /*addr=*/0x200001000000ul, /*len=*/0x1000ul, /*prot=*/0ul, /*flags=MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE*/ 0x32ul, /*fd=*/(intptr_t)-1, /*offset=*/0ul); setup_sysctl(); const char* reason; (void)reason; if ((reason = setup_binfmt_misc())) printf("the reproducer may not work as expected: binfmt_misc setup failed: " "%s\n", reason); if ((reason = setup_swap())) printf("the reproducer may not work as expected: swap setup failed: %s\n", reason); install_segv_handler(); for (procid = 0; procid < 5; procid++) { if (fork() == 0) { do_sandbox_none(); } } sleep(1000000); return 0; }