Syzkaller hit 'memory leak in kobject_set_name_vargs' bug. BUG: memory leak unreferenced object 0xffff8880090bd800 (size 32): comm "syz-executor627", pid 267, jiffies 4294959342 (age 14.092s) hex dump (first 32 bytes): 39 70 2d 66 63 61 6c 6c 2d 63 61 63 68 65 2d 33 9p-fcall-cache-3 00 d9 0b 09 80 88 ff ff 5f 74 3a 73 30 00 00 00 ........_t:s0... backtrace: [<00000000a8e4269d>] kstrdup+0x36/0x70 mm/util.c:60 [<000000004c6f70a3>] kstrdup_const+0x53/0x80 mm/util.c:83 [<000000003a89c4d4>] kvasprintf_const+0x10c/0x1a0 lib/kasprintf.c:48 [<000000006dc29d43>] kobject_set_name_vargs+0x56/0x150 lib/kobject.c:297 [<000000001cd2e7f6>] kobject_add_varg lib/kobject.c:392 [inline] [<000000001cd2e7f6>] kobject_init_and_add+0xc9/0x160 lib/kobject.c:481 [<0000000005a6569b>] sysfs_slab_add+0x172/0x200 mm/slub.c:5626 [<000000007e9efc85>] __kmem_cache_create+0x3db/0x520 mm/slub.c:4445 [<000000006402f76b>] create_cache mm/slab_common.c:255 [inline] [<000000006402f76b>] kmem_cache_create_usercopy+0x1db/0x2f0 mm/slab_common.c:350 [<000000001658960c>] p9_client_create+0xc6a/0x1230 net/9p/client.c:1074 [<000000008988e086>] v9fs_session_init+0x1dd/0x1680 fs/9p/v9fs.c:406 [<00000000ad2dc19a>] v9fs_mount+0x79/0x8f0 fs/9p/vfs_super.c:126 [<0000000022eae919>] legacy_get_tree+0x105/0x220 fs/fs_context.c:593 [<0000000077d66410>] vfs_get_tree+0x8e/0x300 fs/super.c:1572 [<00000000c91fed1c>] do_new_mount fs/namespace.c:2917 [inline] [<00000000c91fed1c>] path_mount+0x1429/0x2120 fs/namespace.c:3247 [<00000000c61d6399>] do_mount fs/namespace.c:3260 [inline] [<00000000c61d6399>] __do_sys_mount fs/namespace.c:3468 [inline] [<00000000c61d6399>] __se_sys_mount fs/namespace.c:3445 [inline] [<00000000c61d6399>] __x64_sys_mount+0x282/0x300 fs/namespace.c:3445 [<0000000019981772>] do_syscall_64+0x33/0x40 arch/x86/entry/common.c:46 Syzkaller reproducer: # {Threaded:false Collide:false Repeat:true RepeatTimes:0 Procs:1 Slowdown:1 Sandbox: Leak:true NetInjection:false NetDevices:false NetReset:false Cgroups:false BinfmtMisc:false CloseFDs:false KCSAN:false DevlinkPCI:false USB:false VhciInjection:false Wifi:false IEEE802154:false Sysctl:false UseTmpDir:false HandleSegv:false Repro:false Trace:false LegacyOptions:{Fault:false FaultCall:0 FaultNth:0}} openat(0xffffffffffffff9c, &(0x7f0000000040)='./file0\x00', 0x644e2, 0x0) pipe(&(0x7f00000001c0)={0xffffffffffffffff, 0xffffffffffffffff}) mount$9p_fd(0x0, &(0x7f0000000040)='./file0\x00', &(0x7f0000000000), 0x0, &(0x7f0000000080)=ANY=[@ANYBLOB='trans=fd,rfdno=', @ANYRESHEX=r0, @ANYBLOB=',wfdno=', @ANYRESHEX=r1, @ANYBLOB]) (fail_nth: 60) C reproducer: // 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 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 inject_fault(int nth) { int fd; fd = open("/proc/thread-self/fail-nth", O_RDWR); if (fd == -1) exit(1); char buf[16]; sprintf(buf, "%d", nth); if (write(fd, buf, strlen(buf)) != (ssize_t)strlen(buf)) exit(1); return fd; } 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 setup_fault() { static struct { const char* file; const char* val; bool fatal; } files[] = { {"/sys/kernel/debug/failslab/ignore-gfp-wait", "N", true}, {"/sys/kernel/debug/fail_futex/ignore-private", "N", false}, {"/sys/kernel/debug/fail_page_alloc/ignore-gfp-highmem", "N", false}, {"/sys/kernel/debug/fail_page_alloc/ignore-gfp-wait", "N", false}, {"/sys/kernel/debug/fail_page_alloc/min-order", "0", false}, }; unsigned i; for (i = 0; i < sizeof(files) / sizeof(files[0]); i++) { if (!write_file(files[i].file, files[i].val)) { if (files[i].fatal) exit(1); } } } #define KMEMLEAK_FILE "/sys/kernel/debug/kmemleak" static void setup_leak() { if (!write_file(KMEMLEAK_FILE, "scan")) exit(1); sleep(5); if (!write_file(KMEMLEAK_FILE, "scan")) exit(1); if (!write_file(KMEMLEAK_FILE, "clear")) exit(1); } static void check_leaks(void) { int fd = open(KMEMLEAK_FILE, O_RDWR); if (fd == -1) exit(1); uint64_t start = current_time_ms(); if (write(fd, "scan", 4) != 4) exit(1); sleep(1); while (current_time_ms() - start < 4 * 1000) sleep(1); if (write(fd, "scan", 4) != 4) exit(1); static char buf[128 << 10]; ssize_t n = read(fd, buf, sizeof(buf) - 1); if (n < 0) exit(1); int nleaks = 0; if (n != 0) { sleep(1); if (write(fd, "scan", 4) != 4) exit(1); if (lseek(fd, 0, SEEK_SET) < 0) exit(1); n = read(fd, buf, sizeof(buf) - 1); if (n < 0) exit(1); buf[n] = 0; char* pos = buf; char* end = buf + n; while (pos < end) { char* next = strstr(pos + 1, "unreferenced object"); if (!next) next = end; char prev = *next; *next = 0; fprintf(stderr, "BUG: memory leak\n%s\n", pos); *next = prev; pos = next; nleaks++; } } if (write(fd, "clear", 5) != 5) exit(1); close(fd); if (nleaks) exit(1); } 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(); exit(0); } int status = 0; uint64_t start = current_time_ms(); for (;;) { if (waitpid(-1, &status, WNOHANG | WAIT_FLAGS) == pid) break; sleep_ms(1); if (current_time_ms() - start < 5000) continue; kill_and_wait(pid, &status); break; } check_leaks(); } } uint64_t r[2] = {0xffffffffffffffff, 0xffffffffffffffff}; void execute_one(void) { intptr_t res = 0; memcpy((void*)0x20000040, "./file0\000", 8); syscall(__NR_openat, 0xffffff9c, 0x20000040ul, 0x644e2ul, 0ul); res = syscall(__NR_pipe, 0x200001c0ul); if (res != -1) { r[0] = *(uint32_t*)0x200001c0; r[1] = *(uint32_t*)0x200001c4; } memcpy((void*)0x20000040, "./file0\000", 8); memcpy((void*)0x20000000, "9p\000", 3); memcpy((void*)0x20000080, "trans=fd,rfdno=", 15); sprintf((char*)0x2000008f, "0x%016llx", (long long)r[0]); memcpy((void*)0x200000a1, ",wfdno=", 7); sprintf((char*)0x200000a8, "0x%016llx", (long long)r[1]); inject_fault(60); syscall(__NR_mount, 0ul, 0x20000040ul, 0x20000000ul, 0ul, 0x20000080ul); } 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); setup_leak(); setup_fault(); loop(); return 0; }