Syzkaller hit 'memory leak in iovec_from_user' bug. executing program executing program BUG: memory leak unreferenced object 0xffff8880157f8d00 (size 192): comm "syz-executor404", pid 276, jiffies 4294821224 (age 22.851s) hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace: [<00000000a674df4c>] iovec_from_user+0x349/0x3c0 [<00000000b9cbe063>] __import_iovec+0x64/0x5c0 [<00000000f3833d1c>] __io_import_iovec+0x26c/0x13b0 [<00000000c2a11605>] io_read+0xaf4/0x12a0 [<00000000d5b62e88>] io_issue_sqe+0x2812/0x8e50 [<000000007db01a6d>] io_submit_sqes+0x1132/0x9560 [<00000000f15f2b0e>] __do_sys_io_uring_enter+0xa17/0x1520 [<000000002d0f7458>] do_syscall_64+0x3b/0x90 [<00000000aebdccbe>] entry_SYSCALL_64_after_hwframe+0x44/0xae BUG: memory leak unreferenced object 0xffff88801d2ae000 (size 192): comm "syz-executor404", pid 277, jiffies 4294830634 (age 13.441s) hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace: [<00000000a674df4c>] iovec_from_user+0x349/0x3c0 [<00000000b9cbe063>] __import_iovec+0x64/0x5c0 [<00000000f3833d1c>] __io_import_iovec+0x26c/0x13b0 [<00000000c2a11605>] io_read+0xaf4/0x12a0 [<00000000d5b62e88>] io_issue_sqe+0x2812/0x8e50 [<000000007db01a6d>] io_submit_sqes+0x1132/0x9560 [<00000000f15f2b0e>] __do_sys_io_uring_enter+0xa17/0x1520 [<000000002d0f7458>] do_syscall_64+0x3b/0x90 [<00000000aebdccbe>] 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 = syz_io_uring_setup(0xeaf, &(0x7f0000000140), &(0x7f0000ffc000/0x3000)=nil, &(0x7f0000ffe000/0x2000)=nil, &(0x7f0000000100)=0x0, &(0x7f0000000080)=0x0) r3 = syz_open_dev$tty1(0xc, 0x4, 0x1) syz_io_uring_submit(r1, r2, &(0x7f0000000000)=@IORING_OP_READV=@pass_iovec={0x1, 0x0, 0x0, @fd=r3, 0x8001, &(0x7f00000008c0)=[{0x0}, {0x0}, {0x0}, {0x0}, {0x0}, {0x0}, {0x0}, {0x0}, {0x0}], 0x9, 0x15}, 0x0) io_uring_enter(r0, 0x100001, 0x0, 0x0, 0x0, 0x0) 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 #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; } #define SIZEOF_IO_URING_SQE 64 #define SIZEOF_IO_URING_CQE 16 #define SQ_HEAD_OFFSET 0 #define SQ_TAIL_OFFSET 64 #define SQ_RING_MASK_OFFSET 256 #define SQ_RING_ENTRIES_OFFSET 264 #define SQ_FLAGS_OFFSET 276 #define SQ_DROPPED_OFFSET 272 #define CQ_HEAD_OFFSET 128 #define CQ_TAIL_OFFSET 192 #define CQ_RING_MASK_OFFSET 260 #define CQ_RING_ENTRIES_OFFSET 268 #define CQ_RING_OVERFLOW_OFFSET 284 #define CQ_FLAGS_OFFSET 280 #define CQ_CQES_OFFSET 320 struct io_sqring_offsets { uint32_t head; uint32_t tail; uint32_t ring_mask; uint32_t ring_entries; uint32_t flags; uint32_t dropped; uint32_t array; uint32_t resv1; uint64_t resv2; }; struct io_cqring_offsets { uint32_t head; uint32_t tail; uint32_t ring_mask; uint32_t ring_entries; uint32_t overflow; uint32_t cqes; uint64_t resv[2]; }; struct io_uring_params { uint32_t sq_entries; uint32_t cq_entries; uint32_t flags; uint32_t sq_thread_cpu; uint32_t sq_thread_idle; uint32_t features; uint32_t resv[4]; struct io_sqring_offsets sq_off; struct io_cqring_offsets cq_off; }; #define IORING_OFF_SQ_RING 0 #define IORING_OFF_SQES 0x10000000ULL #define sys_io_uring_setup 425 static long syz_io_uring_setup(volatile long a0, volatile long a1, volatile long a2, volatile long a3, volatile long a4, volatile long a5) { uint32_t entries = (uint32_t)a0; struct io_uring_params* setup_params = (struct io_uring_params*)a1; void* vma1 = (void*)a2; void* vma2 = (void*)a3; void** ring_ptr_out = (void**)a4; void** sqes_ptr_out = (void**)a5; uint32_t fd_io_uring = syscall(sys_io_uring_setup, entries, setup_params); uint32_t sq_ring_sz = setup_params->sq_off.array + setup_params->sq_entries * sizeof(uint32_t); uint32_t cq_ring_sz = setup_params->cq_off.cqes + setup_params->cq_entries * SIZEOF_IO_URING_CQE; uint32_t ring_sz = sq_ring_sz > cq_ring_sz ? sq_ring_sz : cq_ring_sz; *ring_ptr_out = mmap(vma1, ring_sz, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_POPULATE | MAP_FIXED, fd_io_uring, IORING_OFF_SQ_RING); uint32_t sqes_sz = setup_params->sq_entries * SIZEOF_IO_URING_SQE; *sqes_ptr_out = mmap(vma2, sqes_sz, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_POPULATE | MAP_FIXED, fd_io_uring, IORING_OFF_SQES); return fd_io_uring; } static long syz_io_uring_submit(volatile long a0, volatile long a1, volatile long a2, volatile long a3) { char* ring_ptr = (char*)a0; char* sqes_ptr = (char*)a1; char* sqe = (char*)a2; uint32_t sqes_index = (uint32_t)a3; uint32_t sq_ring_entries = *(uint32_t*)(ring_ptr + SQ_RING_ENTRIES_OFFSET); uint32_t cq_ring_entries = *(uint32_t*)(ring_ptr + CQ_RING_ENTRIES_OFFSET); uint32_t sq_array_off = (CQ_CQES_OFFSET + cq_ring_entries * SIZEOF_IO_URING_CQE + 63) & ~63; if (sq_ring_entries) sqes_index %= sq_ring_entries; char* sqe_dest = sqes_ptr + sqes_index * SIZEOF_IO_URING_SQE; memcpy(sqe_dest, sqe, SIZEOF_IO_URING_SQE); uint32_t sq_ring_mask = *(uint32_t*)(ring_ptr + SQ_RING_MASK_OFFSET); uint32_t* sq_tail_ptr = (uint32_t*)(ring_ptr + SQ_TAIL_OFFSET); uint32_t sq_tail = *sq_tail_ptr & sq_ring_mask; uint32_t sq_tail_next = *sq_tail_ptr + 1; uint32_t* sq_array = (uint32_t*)(ring_ptr + sq_array_off); *(sq_array + sq_tail) = sqes_index; __atomic_store_n(sq_tail_ptr, sq_tail_next, __ATOMIC_RELEASE); return 0; } static long syz_open_dev(volatile long a0, volatile long a1, volatile long a2) { if (a0 == 0xc || a0 == 0xb) { char buf[128]; sprintf(buf, "/dev/%s/%d:%d", a0 == 0xc ? "char" : "block", (uint8_t)a1, (uint8_t)a2); return open(buf, O_RDWR, 0); } else { char buf[1024]; char* hash; strncpy(buf, (char*)a0, sizeof(buf) - 1); buf[sizeof(buf) - 1] = 0; while ((hash = strchr(buf, '#'))) { *hash = '0' + (char)(a1 % 10); a1 /= 10; } return open(buf, a2, 0); } } 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"); } #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(); } } #ifndef __NR_io_uring_enter #define __NR_io_uring_enter 426 #endif uint64_t r[4] = {0xffffffffffffffff, 0x0, 0x0, 0xffffffffffffffff}; void execute_one(void) { intptr_t res = 0; *(uint32_t*)0x20000144 = 0; *(uint32_t*)0x20000148 = 0; *(uint32_t*)0x2000014c = 0; *(uint32_t*)0x20000150 = 0; *(uint32_t*)0x20000158 = -1; memset((void*)0x2000015c, 0, 12); res = -1; res = syz_io_uring_setup(0xeaf, 0x20000140, 0x20ffc000, 0x20ffe000, 0x20000100, 0x20000080); if (res != -1) { r[0] = res; r[1] = *(uint64_t*)0x20000100; r[2] = *(uint64_t*)0x20000080; } res = -1; res = syz_open_dev(0xc, 4, 1); if (res != -1) r[3] = res; *(uint8_t*)0x20000000 = 1; *(uint8_t*)0x20000001 = 0; *(uint16_t*)0x20000002 = 0; *(uint32_t*)0x20000004 = r[3]; *(uint64_t*)0x20000008 = 0x8001; *(uint64_t*)0x20000010 = 0x200008c0; *(uint64_t*)0x200008c0 = 0; *(uint64_t*)0x200008c8 = 0; *(uint64_t*)0x200008d0 = 0; *(uint64_t*)0x200008d8 = 0; *(uint64_t*)0x200008e0 = 0; *(uint64_t*)0x200008e8 = 0; *(uint64_t*)0x200008f0 = 0; *(uint64_t*)0x200008f8 = 0; *(uint64_t*)0x20000900 = 0; *(uint64_t*)0x20000908 = 0; *(uint64_t*)0x20000910 = 0; *(uint64_t*)0x20000918 = 0; *(uint64_t*)0x20000920 = 0; *(uint64_t*)0x20000928 = 0; *(uint64_t*)0x20000930 = 0; *(uint64_t*)0x20000938 = 0; *(uint64_t*)0x20000940 = 0; *(uint64_t*)0x20000948 = 0; *(uint32_t*)0x20000018 = 9; *(uint32_t*)0x2000001c = 0x15; *(uint64_t*)0x20000020 = 0; *(uint16_t*)0x20000028 = 0; *(uint16_t*)0x2000002a = 0; memset((void*)0x2000002c, 0, 20); syz_io_uring_submit(r[1], r[2], 0x20000000, 0); syscall(__NR_io_uring_enter, r[0], 0x100001, 0, 0ul, 0ul, 0ul); } 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(); loop(); return 0; }