kmalloc include/linux/slab.h:493 [inline] user_preparse+0x85/0x190 security/keys/user_defined.c:71 key_create_or_update+0x362/0xaa0 security/keys/key.c:858 ====================================================== WARNING: possible circular locking dependency detected 4.14.307-syzkaller #0 Not tainted ------------------------------------------------------ SYSC_add_key security/keys/keyctl.c:123 [inline] SyS_add_key+0x186/0x370 security/keys/keyctl.c:63 syz-executor.1/8708 is trying to acquire lock: ( &bdev->bd_mutex){+.+.} , at: [] blkdev_reread_part+0x1b/0x40 block/ioctl.c:192 but task is already holding lock: ( do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 &nbd->config_lock){+.+.} entry_SYSCALL_64_after_hwframe+0x5e/0xd3 , at: [] nbd_ioctl+0x11f/0xad0 drivers/block/nbd.c:1369 RIP: 0033:0x7f50528780f9 which lock already depends on the new lock. RSP: 002b:00007f5050dea168 EFLAGS: 00000246 the existing dependency chain (in reverse order) is: ORIG_RAX: 00000000000000f8 -> #2 RAX: ffffffffffffffda RBX: 00007f5052997f80 RCX: 00007f50528780f9 ( RDX: 0000000020000080 RSI: 0000000020000040 RDI: 0000000020000000 &nbd->config_lock RBP: 00007f5050dea1d0 R08: fffffffffffffffb R09: 0000000000000000 ){+.+.} R10: 0000000000000048 R11: 0000000000000246 R12: 0000000000000001 : R13: 00007ffc287a795f R14: 00007f5050dea300 R15: 0000000000022000 __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0xc4/0x1310 kernel/locking/mutex.c:893 nbd_open+0x1ac/0x370 drivers/block/nbd.c:1422 __blkdev_get+0x306/0x1090 fs/block_dev.c:1470 blkdev_get+0x88/0x890 fs/block_dev.c:1611 blkdev_open+0x1cc/0x250 fs/block_dev.c:1772 do_dentry_open+0x44b/0xec0 fs/open.c:777 vfs_open+0x105/0x220 fs/open.c:888 do_last fs/namei.c:3428 [inline] path_openat+0x628/0x2970 fs/namei.c:3571 do_filp_open+0x179/0x3c0 fs/namei.c:3605 do_sys_open+0x296/0x410 fs/open.c:1081 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x5e/0xd3 -> #1 (nbd_index_mutex){+.+.}: __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0xc4/0x1310 kernel/locking/mutex.c:893 nbd_open+0x1e/0x370 drivers/block/nbd.c:1409 __blkdev_get+0x306/0x1090 fs/block_dev.c:1470 blkdev_get+0x88/0x890 fs/block_dev.c:1611 blkdev_open+0x1cc/0x250 fs/block_dev.c:1772 do_dentry_open+0x44b/0xec0 fs/open.c:777 vfs_open+0x105/0x220 fs/open.c:888 do_last fs/namei.c:3428 [inline] path_openat+0x628/0x2970 fs/namei.c:3571 do_filp_open+0x179/0x3c0 fs/namei.c:3605 do_sys_open+0x296/0x410 fs/open.c:1081 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x5e/0xd3 -> #0 (&bdev->bd_mutex){+.+.}: lock_acquire+0x170/0x3f0 kernel/locking/lockdep.c:3998 __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0xc4/0x1310 kernel/locking/mutex.c:893 blkdev_reread_part+0x1b/0x40 block/ioctl.c:192 nbd_bdev_reset drivers/block/nbd.c:1076 [inline] nbd_clear_sock_ioctl drivers/block/nbd.c:1282 [inline] __nbd_ioctl drivers/block/nbd.c:1306 [inline] nbd_ioctl+0x802/0xad0 drivers/block/nbd.c:1376 __blkdev_driver_ioctl block/ioctl.c:297 [inline] blkdev_ioctl+0x540/0x1830 block/ioctl.c:594 block_ioctl+0xd9/0x120 fs/block_dev.c:1893 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:500 [inline] do_vfs_ioctl+0x75a/0xff0 fs/ioctl.c:684 SYSC_ioctl fs/ioctl.c:701 [inline] SyS_ioctl+0x7f/0xb0 fs/ioctl.c:692 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x5e/0xd3 other info that might help us debug this: Chain exists of: &bdev->bd_mutex --> nbd_index_mutex --> &nbd->config_lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&nbd->config_lock); lock(nbd_index_mutex); lock(&nbd->config_lock); lock(&bdev->bd_mutex); *** DEADLOCK *** 1 lock held by syz-executor.1/8708: #0: (&nbd->config_lock){+.+.}, at: [] nbd_ioctl+0x11f/0xad0 drivers/block/nbd.c:1369 stack backtrace: CPU: 1 PID: 8708 Comm: syz-executor.1 Not tainted 4.14.307-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/02/2023 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x1b2/0x281 lib/dump_stack.c:58 print_circular_bug.constprop.0.cold+0x2d7/0x41e kernel/locking/lockdep.c:1258 check_prev_add kernel/locking/lockdep.c:1905 [inline] check_prevs_add kernel/locking/lockdep.c:2022 [inline] validate_chain kernel/locking/lockdep.c:2464 [inline] __lock_acquire+0x2e0e/0x3f20 kernel/locking/lockdep.c:3491 lock_acquire+0x170/0x3f0 kernel/locking/lockdep.c:3998 __mutex_lock_common kernel/locking/mutex.c:756 [inline] __mutex_lock+0xc4/0x1310 kernel/locking/mutex.c:893 blkdev_reread_part+0x1b/0x40 block/ioctl.c:192 nbd_bdev_reset drivers/block/nbd.c:1076 [inline] nbd_clear_sock_ioctl drivers/block/nbd.c:1282 [inline] __nbd_ioctl drivers/block/nbd.c:1306 [inline] nbd_ioctl+0x802/0xad0 drivers/block/nbd.c:1376 __blkdev_driver_ioctl block/ioctl.c:297 [inline] blkdev_ioctl+0x540/0x1830 block/ioctl.c:594 block_ioctl+0xd9/0x120 fs/block_dev.c:1893 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:500 [inline] do_vfs_ioctl+0x75a/0xff0 fs/ioctl.c:684 SYSC_ioctl fs/ioctl.c:701 [inline] SyS_ioctl+0x7f/0xb0 fs/ioctl.c:692 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x5e/0xd3 RIP: 0033:0x7fb225a600f9 RSP: 002b:00007fb223fd2168 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007fb225b7ff80 RCX: 00007fb225a600f9 RDX: 0000000000000000 RSI: 000000000000ab04 RDI: 0000000000000004 RBP: 00007fb225abbae9 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ffebb0ba4bf R14: 00007fb223fd2300 R15: 0000000000022000 FAULT_INJECTION: forcing a failure. name failslab, interval 1, probability 0, space 0, times 0 CPU: 0 PID: 8732 Comm: syz-executor.5 Not tainted 4.14.307-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/02/2023 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x1b2/0x281 lib/dump_stack.c:58 fail_dump lib/fault-inject.c:51 [inline] should_fail.cold+0x10a/0x149 lib/fault-inject.c:149 should_failslab+0xd6/0x130 mm/failslab.c:32 slab_pre_alloc_hook mm/slab.h:421 [inline] slab_alloc mm/slab.c:3376 [inline] kmem_cache_alloc_trace+0x29a/0x3d0 mm/slab.c:3616 kmalloc include/linux/slab.h:488 [inline] kzalloc include/linux/slab.h:661 [inline] assoc_array_insert+0xb9/0x2820 lib/assoc_array.c:998 __key_link_begin+0x106/0x2b0 security/keys/keyring.c:1234 key_create_or_update+0x3c5/0xaa0 security/keys/key.c:871 SYSC_add_key security/keys/keyctl.c:123 [inline] SyS_add_key+0x186/0x370 security/keys/keyctl.c:63 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x5e/0xd3 RIP: 0033:0x7f50528780f9 RSP: 002b:00007f5050dea168 EFLAGS: 00000246 ORIG_RAX: 00000000000000f8 RAX: ffffffffffffffda RBX: 00007f5052997f80 RCX: 00007f50528780f9 RDX: 0000000020000080 RSI: 0000000020000040 RDI: 0000000020000000 RBP: 00007f5050dea1d0 R08: fffffffffffffffb R09: 0000000000000000 R10: 0000000000000048 R11: 0000000000000246 R12: 0000000000000001 R13: 00007ffc287a795f R14: 00007f5050dea300 R15: 0000000000022000 Bluetooth: Unexpected continuation frame (len 19) Bluetooth: Unexpected continuation frame (len 19) Bluetooth: Unexpected continuation frame (len 19) Bluetooth: Unexpected continuation frame (len 19) Bluetooth: Unexpected continuation frame (len 19)