Syzkaller hit 'memory leak in mas_node_count' bug. BUG: memory leak unreferenced object 0xffff88800bd7f800 (size 256): comm "syz-executor192", pid 272, jiffies 4294792897 (age 19.284s) hex dump (first 32 bytes): 09 7b 2a 18 80 88 ff ff ff df fe 20 00 00 00 00 .{*........ .... ff ff fe 20 00 00 00 00 00 00 00 00 00 00 00 00 ... ............ backtrace: [<00000000416e5de1>] mas_alloc_nodes+0x2f4/0x600 [<000000006dc5c25c>] mas_node_count+0x101/0x130 [<000000008cb10b1b>] mas_root_expand.isra.0+0xe5/0xa60 [<00000000d6aa11af>] mas_wr_store_entry.isra.0+0x33c/0x10e0 [<00000000aee1bbff>] mas_store_gfp+0xca/0x1f0 [<0000000003b672f9>] do_mas_align_munmap.constprop.0+0x487/0xc00 [<000000007dda85a8>] do_mas_munmap+0x1ed/0x2c0 [<00000000d6c68dc5>] mmap_region+0x21c/0x1a80 [<00000000b0a0b6b4>] do_mmap+0x82a/0xf60 [<00000000755ba0a3>] do_shmat+0xe42/0x10d0 [<000000002cba1fe0>] __x64_sys_shmat+0xcc/0x160 [<00000000a73d56de>] do_syscall_64+0x3b/0x90 [<00000000f550a033>] entry_SYSCALL_64_after_hwframe+0x44/0xae BUG: memory leak unreferenced object 0xffff88800bd7fe00 (size 256): comm "syz-executor192", pid 273, jiffies 4294800409 (age 11.772s) hex dump (first 32 bytes): 09 fb 27 10 80 88 ff ff ff df fe 20 00 00 00 00 ..'........ .... ff ff fe 20 00 00 00 00 00 00 00 00 00 00 00 00 ... ............ backtrace: [<00000000416e5de1>] mas_alloc_nodes+0x2f4/0x600 [<000000006dc5c25c>] mas_node_count+0x101/0x130 [<000000008cb10b1b>] mas_root_expand.isra.0+0xe5/0xa60 [<00000000d6aa11af>] mas_wr_store_entry.isra.0+0x33c/0x10e0 [<00000000aee1bbff>] mas_store_gfp+0xca/0x1f0 [<0000000003b672f9>] do_mas_align_munmap.constprop.0+0x487/0xc00 [<000000007dda85a8>] do_mas_munmap+0x1ed/0x2c0 [<00000000d6c68dc5>] mmap_region+0x21c/0x1a80 [<00000000b0a0b6b4>] do_mmap+0x82a/0xf60 [<00000000755ba0a3>] do_shmat+0xe42/0x10d0 [<000000002cba1fe0>] __x64_sys_shmat+0xcc/0x160 [<00000000a73d56de>] do_syscall_64+0x3b/0x90 [<00000000f550a033>] entry_SYSCALL_64_after_hwframe+0x44/0xae 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}} r0 = shmget$private(0x0, 0x14000, 0x0, &(0x7f0000fe7000/0x14000)=nil) shmat(r0, &(0x7f0000fe6000/0x4000)=nil, 0x6000) shmat(r0, &(0x7f0000ff0000/0x3000)=nil, 0x4000) shmat(0x0, &(0x7f0000fee000/0x2000)=nil, 0x4000) (fail_nth: 11) 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[1] = {0x0}; void execute_one(void) { intptr_t res = 0; res = syscall(__NR_shmget, 0ul, 0x14000ul, 0ul, 0x20fe7000ul); if (res != -1) r[0] = res; syscall(__NR_shmat, r[0], 0x20fe6000ul, 0x6000ul); syscall(__NR_shmat, r[0], 0x20ff0000ul, 0x4000ul); inject_fault(11); syscall(__NR_shmat, 0, 0x20fee000ul, 0x4000ul); } 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; }