Hi, We would like to report the following bug which has been found by our modified version of syzkaller. ====================================================== description: general protection fault in start_motor affected file: drivers/block/floppy.c kernel version: 5.10.131 kernel commit: de62055f423f5dcb548f74cebd68f03c8903f73a git tree: upstream kernel config: https://syzkaller.appspot.com/x/.config?x=e49433cfed49b7d9 crash reproducer: attached ====================================================== Crash log: ====================================================== general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007] CPU: 0 PID: 8820 Comm: kworker/u4:48 Tainted: G OE 5.10.131+ #3 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014 Workqueue: floppy fd_timer_workfn RIP: 0010:start_motor+0x3a/0x3f0 drivers/block/floppy.c:1905 Code: 08 e8 4a 15 1c fd 48 8b 1d 03 30 4d 0b 48 b8 00 00 00 00 00 fc ff df 0f b6 2d 72 22 4d 0b 48 89 da 48 c1 ea 03 89 e9 41 89 ed <0f> b6 04 02 83 e1 03 41 83 e5 03 84 c0 74 08 3c 03 0f 8e be 02 00 RSP: 0018:ffffc90000a47cc0 EFLAGS: 00010246 RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffffffff845483d6 RDI: ffffffff84549f90 RBP: 0000000000000000 R08: ffff88803a2b1ac0 R09: fffffbfff19dad22 R10: 0000000000000000 R11: 0000000000000000 R12: ffffffff84549f90 R13: 0000000000000000 R14: ffff88810c148000 R15: ffff888100069800 FS: 0000000000000000(0000) GS:ffff88811a000000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000001b2fb22000 CR3: 000000002daa9001 CR4: 0000000000170ef0 Call Trace: floppy_ready+0x7f/0x1950 drivers/block/floppy.c:1932 process_one_work+0x953/0x15c0 kernel/workqueue.c:2279 worker_thread+0x96/0xe20 kernel/workqueue.c:2425 kthread+0x374/0x490 kernel/kthread.c:313 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296 Modules linked in: uio_ivshmem(OE) uio(E) ---[ end trace 345300e45e5eb538 ]--- RIP: 0010:start_motor+0x3a/0x3f0 drivers/block/floppy.c:1905 Code: 08 e8 4a 15 1c fd 48 8b 1d 03 30 4d 0b 48 b8 00 00 00 00 00 fc ff df 0f b6 2d 72 22 4d 0b 48 89 da 48 c1 ea 03 89 e9 41 89 ed <0f> b6 04 02 83 e1 03 41 83 e5 03 84 c0 74 08 3c 03 0f 8e be 02 00 RSP: 0018:ffffc90000a47cc0 EFLAGS: 00010246 RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffffffff845483d6 RDI: ffffffff84549f90 RBP: 0000000000000000 R08: ffff88803a2b1ac0 R09: fffffbfff19dad22 R10: 0000000000000000 R11: 0000000000000000 R12: ffffffff84549f90 R13: 0000000000000000 R14: ffff88810c148000 R15: ffff888100069800 FS: 0000000000000000(0000) GS:ffff88811a000000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fee2b352038 CR3: 00000000425db005 CR4: 0000000000170ef0 ---------------- Code disassembly (best guess): 0: 08 e8 or %ch,%al 2: 4a 15 1c fd 48 8b rex.WX adc $0xffffffff8b48fd1c,%rax 8: 1d 03 30 4d 0b sbb $0xb4d3003,%eax d: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax 14: fc ff df 17: 0f b6 2d 72 22 4d 0b movzbl 0xb4d2272(%rip),%ebp # 0xb4d2290 1e: 48 89 da mov %rbx,%rdx 21: 48 c1 ea 03 shr $0x3,%rdx 25: 89 e9 mov %ebp,%ecx 27: 41 89 ed mov %ebp,%r13d * 2a: 0f b6 04 02 movzbl (%rdx,%rax,1),%eax <-- trapping instruction 2e: 83 e1 03 and $0x3,%ecx 31: 41 83 e5 03 and $0x3,%r13d 35: 84 c0 test %al,%al 37: 74 08 je 0x41 39: 3c 03 cmp $0x3,%al 3b: 0f .byte 0xf 3c: 8e .byte 0x8e 3d: be .byte 0xbe 3e: 02 00 add (%rax),%al -- Thanks and Regards, Dipanjan
// autogenerated by syzkaller (https://github.com/google/syzkaller) #define _GNU_SOURCE #include <dirent.h> #include <endian.h> #include <errno.h> #include <fcntl.h> #include <pthread.h> #include <signal.h> #include <stdarg.h> #include <stdbool.h> #include <stdint.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <sys/prctl.h> #include <sys/stat.h> #include <sys/syscall.h> #include <sys/types.h> #include <sys/wait.h> #include <time.h> #include <unistd.h> #include <linux/futex.h> static unsigned long long procid; 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 void thread_start(void* (*fn)(void*), void* arg) { pthread_t th; pthread_attr_t attr; pthread_attr_init(&attr); pthread_attr_setstacksize(&attr, 128 << 10); int i = 0; for (; i < 100; i++) { if (pthread_create(&th, &attr, fn, arg) == 0) { pthread_attr_destroy(&attr); return; } if (errno == EAGAIN) { usleep(50); continue; } break; } exit(1); } typedef struct { int state; } event_t; static void event_init(event_t* ev) { ev->state = 0; } static void event_reset(event_t* ev) { ev->state = 0; } static void event_set(event_t* ev) { if (ev->state) exit(1); __atomic_store_n(&ev->state, 1, __ATOMIC_RELEASE); syscall(SYS_futex, &ev->state, FUTEX_WAKE | FUTEX_PRIVATE_FLAG, 1000000); } static void event_wait(event_t* ev) { while (!__atomic_load_n(&ev->state, __ATOMIC_ACQUIRE)) syscall(SYS_futex, &ev->state, FUTEX_WAIT | FUTEX_PRIVATE_FLAG, 0, 0); } static int event_isset(event_t* ev) { return __atomic_load_n(&ev->state, __ATOMIC_ACQUIRE); } static int event_timedwait(event_t* ev, uint64_t timeout) { uint64_t start = current_time_ms(); uint64_t now = start; for (;;) { uint64_t remain = timeout - (now - start); struct timespec ts; ts.tv_sec = remain / 1000; ts.tv_nsec = (remain % 1000) * 1000 * 1000; syscall(SYS_futex, &ev->state, FUTEX_WAIT | FUTEX_PRIVATE_FLAG, 0, &ts); if (__atomic_load_n(&ev->state, __ATOMIC_ACQUIRE)) return 1; now = current_time_ms(); if (now - start > timeout) return 0; } } 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 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"); } struct thread_t { int created, call; event_t ready, done; }; static struct thread_t threads[16]; static void execute_call(int call); static int running; static void* thr(void* arg) { struct thread_t* th = (struct thread_t*)arg; for (;;) { event_wait(&th->ready); event_reset(&th->ready); execute_call(th->call); __atomic_fetch_sub(&running, 1, __ATOMIC_RELAXED); event_set(&th->done); } return 0; } static void execute_one(void) { int i, call, thread; for (call = 0; call < 10; call++) { for (thread = 0; thread < (int)(sizeof(threads) / sizeof(threads[0])); thread++) { struct thread_t* th = &threads[thread]; if (!th->created) { th->created = 1; event_init(&th->ready); event_init(&th->done); event_set(&th->done); thread_start(thr, th); } if (!event_isset(&th->done)) continue; event_reset(&th->done); th->call = call; __atomic_fetch_add(&running, 1, __ATOMIC_RELAXED); event_set(&th->ready); if (call == 3 || call == 4 || call == 5 || call == 6) break; event_timedwait(&th->done, 50); break; } } for (i = 0; i < 100 && __atomic_load_n(&running, __ATOMIC_RELAXED); i++) sleep_ms(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; } } } uint64_t r[1] = {0xffffffffffffffff}; void execute_call(int call) { intptr_t res = 0; switch (call) { case 0: *(uint16_t*)0x20000040 = 2; *(uint16_t*)0x20000042 = htobe16(0x4e20); *(uint32_t*)0x20000044 = htobe32(0); *(uint8_t*)0x200000c0 = 0; *(uint8_t*)0x200000c1 = 0; *(uint16_t*)0x200000c2 = 0x34; *(uint32_t*)0x200000c4 = 0; memcpy((void*)0x200000c8, "\x4b\x2f\x09\xfc\x47\x61\xb8\x60\xe6\x7f\xe9\x46\xd3\x73\x42\xa7\x1e\x0b\xbe\xe0\xb2\x52\x00\x1f\x8e\x09\xf2\xa4\x0b\x5f\x06\x45\x81\x5e\x6c\xea\xae\x84\x7a\x7f\x50\xa3\xb3\xeb\x07\x7d\x95\x11\x50\x2c\xee\x3d\xee\xdf\xc9\x30\xe6\x6a\x46\x9d\x4e\x88\xcd\x1c\x66\x70\x55\xd0\x7f\x9e\xf9\x5f\x0d\xd1\xd2\x42\x6a\x97\xf5\xed", 80); syscall(__NR_setsockopt, -1, 6, 0xe, 0x20000040ul, 0xd8ul); break; case 1: memcpy((void*)0x200001c0, "/dev/fd#\000", 9); res = -1; res = syz_open_dev(0x200001c0, 0, 3); if (res != -1) r[0] = res; break; case 2: syscall(__NR_ioctl, r[0], 0x241, 0); break; case 3: *(uint16_t*)0x20000040 = 2; *(uint16_t*)0x20000042 = htobe16(0x4e20); *(uint32_t*)0x20000044 = htobe32(0); *(uint8_t*)0x200000c0 = 0; *(uint8_t*)0x200000c1 = 0; *(uint16_t*)0x200000c2 = 0x34; *(uint32_t*)0x200000c4 = 0; memcpy((void*)0x200000c8, "\x4b\x2f\x09\xfc\x47\x61\xb8\x60\xe6\x7f\xe9\x46\xd3\x73\x42\xa7\x1e\x0b\xbe\xe0\xb2\x52\x00\x1f\x8e\x09\xf2\xa4\x0b\x5f\x06\x45\x81\x5e\x6c\xea\xae\x84\x7a\x7f\x50\xa3\xb3\xeb\x07\x7d\x95\x11\x50\x2c\xee\x3d\xee\xdf\xc9\x30\xe6\x6a\x46\x9d\x4e\x88\xcd\x1c\x66\x70\x55\xd0\x7f\x9e\xf9\x5f\x0d\xd1\xd2\x42\x6a\x97\xf5\xed", 80); syscall(__NR_setsockopt, -1, 6, 0xe, 0x20000040ul, 0xd8ul); break; case 4: memcpy((void*)0x20000000, "/dev/fd#\000", 9); syz_open_dev(0x20000000, -1, 0x4000); break; case 5: syscall(__NR_ioctl, r[0], 0x241, 0); break; case 6: syscall(__NR_ioctl, r[0], 0x247, 0); break; case 7: syz_open_dev(0, 8, 0x200); break; case 8: *(uint32_t*)0x20000180 = 2; syscall(__NR_setsockopt, -1, 6, 0x14, 0x20000180ul, 4ul); break; case 9: syscall(__NR_ioctl, r[0], 0x247, 0); break; } } 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); for (procid = 0; procid < 8; procid++) { if (fork() == 0) { loop(); } } sleep(1000000); return 0; }
Attachment:
repro.syz
Description: Binary data
