// https://syzkaller.appspot.com/bug?id=833e9c2f24710d6ca275451770a7693aca5f7339 // 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 #ifndef __NR_memfd_create #define __NR_memfd_create 319 #endif 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; } #define MAX_FDS 30 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 (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); } static void setup_common() { 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); 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 = 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); setup_common(); sandbox_common(); drop_caps(); if (unshare(CLONE_NEWNET)) { } write_file("/proc/sys/net/ipv4/ping_group_range", "0 65535"); sandbox_common_mount_tmpfs(); setup_binderfs(); loop(); exit(1); } static void close_fds() { for (int fd = 3; fd < MAX_FDS; fd++) close(fd); } uint64_t r[3] = {0xffffffffffffffff, 0xffffffffffffffff, 0xffffffffffffffff}; void loop(void) { intptr_t res = 0; if (write(1, "executing program\n", sizeof("executing program\n") - 1)) { } memcpy((void*)0x20000040, "y\0205%\372,\037\231\242\311\216\315\\\372\366\022\225^\337T\342=" "\016~F\315s\243\377\211>" "\204\251\206\206\242F\220\223\230N\005e\222Jw\316c\316\2372\310\002f" "\003\am\b\264H\217\236\245\026\217a\377\262\"\212\025\023\242\027%!" "T\213\241\271-\023\371og\225\235T\357\312hw\365\377u\177u\270*" "\323C\257\302H\a\000\000\000\020\2760\212\272\004\000\000\000\000\000" "\000\000-\302\350\377mv\025\242`z\254eM\326)=" "JW9\217\340\224\326\001\177\251h\337\360[wP\206\002\240R\363#\330," "\261I\366\225\365\205x\322\227\315\242$\260\003u\311\302}" "\313\264\325\032}" "\032\304\245\207\304I\214\316\355\321Y\02752\330Y\a\247^" "\310\350\237\003\000\000\000\000\000\000\000\000\000\000\000\000b\016" "\370\250\032\247\357D\335\244u\320\364\027\314\037n\231\\=" "\353\021\"\263:\206u\247\222\321@\v\256\320@/" "3\360\372\232\226\362\'\304b\031KH\247\035j\234\376", 272); res = syscall(__NR_memfd_create, /*name=*/0x20000040ul, /*flags=MFD_ALLOW_SEALING*/ 2ul); if (res != -1) r[0] = res; syscall(__NR_ftruncate, /*fd=*/r[0], /*len=*/0xfffful); syscall(__NR_fcntl, /*fd=*/r[0], /*cmd=*/0x409ul, /*seals=F_SEAL_GROW|F_SEAL_SHRINK|F_SEAL_SEAL*/ 7ul); memcpy((void*)0x200001c0, "/dev/udmabuf\000", 13); res = syscall(__NR_openat, /*fd=*/0xffffffffffffff9cul, /*file=*/0x200001c0ul, /*flags=*/2ul, 0); if (res != -1) r[1] = res; *(uint32_t*)0x20000000 = r[0]; *(uint32_t*)0x20000004 = 0; *(uint64_t*)0x20000008 = 0; *(uint64_t*)0x20000010 = 0x8000; res = syscall(__NR_ioctl, /*fd=*/r[1], /*cmd=*/0x40187542, /*arg=*/0x20000000ul); if (res != -1) r[2] = res; syscall(__NR_mmap, /*addr=*/0x20667000ul, /*len=*/0x4000ul, /*prot=PROT_GROWSDOWN|PROT_SEM|PROT_WRITE|PROT_EXEC*/ 0x100000eul, /*flags=MAP_STACK|MAP_POPULATE|MAP_FIXED|MAP_SHARED*/ 0x28011ul, /*fd=*/r[2], /*offset=*/0ul); close_fds(); } int main(void) { syscall(__NR_mmap, /*addr=*/0x1ffff000ul, /*len=*/0x1000ul, /*prot=*/0ul, /*flags=MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE*/ 0x32ul, /*fd=*/-1, /*offset=*/0ul); syscall(__NR_mmap, /*addr=*/0x20000000ul, /*len=*/0x1000000ul, /*prot=PROT_WRITE|PROT_READ|PROT_EXEC*/ 7ul, /*flags=MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE*/ 0x32ul, /*fd=*/-1, /*offset=*/0ul); syscall(__NR_mmap, /*addr=*/0x21000000ul, /*len=*/0x1000ul, /*prot=*/0ul, /*flags=MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE*/ 0x32ul, /*fd=*/-1, /*offset=*/0ul); const char* reason; (void)reason; do_sandbox_none(); return 0; }