[ OK ] Started Getty on tty2. [ OK ] Started Getty on tty1. [ OK ] Started Serial Getty on ttyS0. [ OK ] Reached target Login Prompts. [ OK ] Reached target Multi-User System. [ OK ] Reached target Graphical Interface. Starting Update UTMP about System Runlevel Changes... [ OK ] Started Update UTMP about System Runlevel Changes. Starting Load/Save RF Kill Switch Status... [ OK ] Started Load/Save RF Kill Switch Status. Debian GNU/Linux 9 syzkaller ttyS0 Warning: Permanently added '10.128.0.138' (ECDSA) to the list of known hosts. executing program executing program executing program executing program executing program executing program syzkaller login: [ 29.626554] netlink: 4 bytes leftover after parsing attributes in process `syz-executor660'. [ 29.638466] netlink: 4 bytes leftover after parsing attributes in process `syz-executor660'. [ 29.647614] netlink: 4 bytes leftover after parsing attributes in process `syz-executor660'. [ 29.656265] netlink: 4 bytes leftover after parsing attributes in process `syz-executor660'. [ 29.664946] netlink: 4 bytes leftover after parsing attributes in process `syz-executor660'. [ 29.673523] netlink: 4 bytes leftover after parsing attributes in process `syz-executor660'. [ 29.682166] netlink: 4 bytes leftover after parsing attributes in process `syz-executor660'. [ 29.690803] netlink: 4 bytes leftover after parsing attributes in process `syz-executor660'. [ 29.699451] netlink: 4 bytes leftover after parsing attributes in process `syz-executor660'. [ 29.708107] netlink: 4 bytes leftover after parsing attributes in process `syz-executor660'. executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program [ 31.445616] ================================================================== [ 31.453104] BUG: KASAN: use-after-free in refcount_dec_not_one+0x9a/0xc0 [ 31.459946] Read of size 4 at addr ffff88809a9c5d98 by task systemd-udevd/8218 [ 31.467388] [ 31.469010] CPU: 1 PID: 8218 Comm: systemd-udevd Not tainted 4.14.231-syzkaller #0 [ 31.476719] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 31.486105] Call Trace: [ 31.488679] dump_stack+0x1b2/0x281 [ 31.492337] print_address_description.cold+0x54/0x1d3 [ 31.497593] kasan_report_error.cold+0x8a/0x191 [ 31.502241] ? refcount_dec_not_one+0x9a/0xc0 [ 31.506714] __asan_report_load4_noabort+0x68/0x70 [ 31.511711] ? refcount_dec_not_one+0x9a/0xc0 [ 31.517316] refcount_dec_not_one+0x9a/0xc0 [ 31.521627] refcount_dec_and_mutex_lock+0x1a/0x60 [ 31.526539] nbd_release+0xf3/0x150 [ 31.530144] ? nbd_queue_rq+0xc50/0xc50 [ 31.534121] __blkdev_put+0x5aa/0x800 [ 31.537923] ? revalidate_disk+0x1f0/0x1f0 [ 31.542148] ? locks_remove_file+0x2cd/0x420 [ 31.546560] ? blkdev_put+0x75/0x4c0 [ 31.550304] ? blkdev_put+0x4c0/0x4c0 [ 31.554096] blkdev_close+0x86/0xb0 [ 31.557745] __fput+0x25f/0x7a0 [ 31.561012] task_work_run+0x11f/0x190 [ 31.564881] exit_to_usermode_loop+0x1ad/0x200 [ 31.569454] do_syscall_64+0x4a3/0x640 [ 31.573329] entry_SYSCALL_64_after_hwframe+0x46/0xbb [ 31.578585] RIP: 0033:0x7f3bc5ed7270 [ 31.582276] RSP: 002b:00007ffd1c6f2b48 EFLAGS: 00000246 ORIG_RAX: 0000000000000003 [ 31.589978] RAX: 0000000000000000 RBX: 0000000000000007 RCX: 00007f3bc5ed7270 [ 31.597224] RDX: 000000000aba9500 RSI: 0000000000000000 RDI: 0000000000000007 [ 31.604493] RBP: 00007f3bc6d91710 R08: 000000000000004a R09: 0000000000000008 [ 31.611790] R10: 000055c4d58e6348 R11: 0000000000000246 R12: 0000000000000000 [ 31.619106] R13: 000055c4d58de880 R14: 0000000000000003 R15: 000000000000000e [ 31.626436] [ 31.628045] Allocated by task 8198: [ 31.631771] kasan_kmalloc+0xeb/0x160 [ 31.636072] kmem_cache_alloc_trace+0x131/0x3d0 [ 31.640729] nbd_dev_add+0x7c/0x800 [ 31.644337] nbd_genl_connect+0x3a4/0x1400 [ 31.648548] genl_family_rcv_msg+0x572/0xb20 [ 31.652952] genl_rcv_msg+0xaf/0x140 [ 31.656653] netlink_rcv_skb+0x125/0x390 [ 31.660713] genl_rcv+0x24/0x40 [ 31.664023] netlink_unicast+0x437/0x610 [ 31.668068] netlink_sendmsg+0x62e/0xb80 [ 31.672108] sock_sendmsg+0xb5/0x100 [ 31.675807] ___sys_sendmsg+0x6c8/0x800 [ 31.679779] __sys_sendmsg+0xa3/0x120 [ 31.683556] SyS_sendmsg+0x27/0x40 [ 31.687094] do_syscall_64+0x1d5/0x640 [ 31.690983] entry_SYSCALL_64_after_hwframe+0x46/0xbb [ 31.696342] [ 31.697952] Freed by task 8218: [ 31.701306] kasan_slab_free+0xc3/0x1a0 [ 31.705266] kfree+0xc9/0x250 [ 31.708373] nbd_put.part.0+0x100/0x140 [ 31.712462] nbd_config_put+0x62a/0x810 [ 31.716431] nbd_release+0xdf/0x150 [ 31.720039] __blkdev_put+0x5aa/0x800 [ 31.723815] blkdev_close+0x86/0xb0 [ 31.727442] __fput+0x25f/0x7a0 [ 31.730745] task_work_run+0x11f/0x190 [ 31.734615] exit_to_usermode_loop+0x1ad/0x200 [ 31.739217] do_syscall_64+0x4a3/0x640 [ 31.743126] entry_SYSCALL_64_after_hwframe+0x46/0xbb [ 31.748337] [ 31.749992] The buggy address belongs to the object at ffff88809a9c5cc0 [ 31.749992] which belongs to the cache kmalloc-512 of size 512 [ 31.762627] The buggy address is located 216 bytes inside of [ 31.762627] 512-byte region [ffff88809a9c5cc0, ffff88809a9c5ec0) [ 31.774480] The buggy address belongs to the page: [ 31.779397] page:ffffea00026a7140 count:1 mapcount:0 mapping:ffff88809a9c5040 index:0x0 [ 31.787552] flags: 0xfff00000000100(slab) [ 31.791691] raw: 00fff00000000100 ffff88809a9c5040 0000000000000000 0000000100000006 [ 31.799562] raw: ffffea0002af6920 ffffea0002bd7fe0 ffff88813fe80940 0000000000000000 [ 31.807422] page dumped because: kasan: bad access detected [ 31.813134] [ 31.814739] Memory state around the buggy address: [ 31.819651] ffff88809a9c5c80: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb [ 31.826990] ffff88809a9c5d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 31.834356] >ffff88809a9c5d80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 31.841692] ^ [ 31.845818] ffff88809a9c5e00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 31.853153] ffff88809a9c5e80: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc [ 31.860484] ================================================================== [ 31.867819] Disabling lock debugging due to kernel taint [ 31.883839] Kernel panic - not syncing: panic_on_warn set ... [ 31.883839] [ 31.891228] CPU: 0 PID: 8218 Comm: systemd-udevd Tainted: G B 4.14.231-syzkaller #0 [ 31.900166] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 31.909492] Call Trace: [ 31.912059] dump_stack+0x1b2/0x281 [ 31.915662] panic+0x1f9/0x42d [ 31.918871] ? add_taint.cold+0x16/0x16 [ 31.922824] ? ___preempt_schedule+0x16/0x18 [ 31.927222] kasan_end_report+0x43/0x49 [ 31.931171] kasan_report_error.cold+0xa7/0x191 [ 31.935826] ? refcount_dec_not_one+0x9a/0xc0 [ 31.940305] __asan_report_load4_noabort+0x68/0x70 [ 31.945218] ? refcount_dec_not_one+0x9a/0xc0 [ 31.949684] refcount_dec_not_one+0x9a/0xc0 [ 31.953980] refcount_dec_and_mutex_lock+0x1a/0x60 [ 31.958896] nbd_release+0xf3/0x150 [ 31.962496] ? nbd_queue_rq+0xc50/0xc50 [ 31.966452] __blkdev_put+0x5aa/0x800 [ 31.970319] ? revalidate_disk+0x1f0/0x1f0 [ 31.974528] ? locks_remove_file+0x2cd/0x420 [ 31.978922] ? blkdev_put+0x75/0x4c0 [ 31.982610] ? blkdev_put+0x4c0/0x4c0 [ 31.986471] blkdev_close+0x86/0xb0 [ 31.990073] __fput+0x25f/0x7a0 [ 31.993363] task_work_run+0x11f/0x190 [ 31.997231] exit_to_usermode_loop+0x1ad/0x200 [ 32.001798] do_syscall_64+0x4a3/0x640 [ 32.005664] entry_SYSCALL_64_after_hwframe+0x46/0xbb [ 32.010838] RIP: 0033:0x7f3bc5ed7270 [ 32.014533] RSP: 002b:00007ffd1c6f2b48 EFLAGS: 00000246 ORIG_RAX: 0000000000000003 [ 32.022226] RAX: 0000000000000000 RBX: 0000000000000007 RCX: 00007f3bc5ed7270 [ 32.029509] RDX: 000000000aba9500 RSI: 0000000000000000 RDI: 0000000000000007 [ 32.037243] RBP: 00007f3bc6d91710 R08: 000000000000004a R09: 0000000000000008 [ 32.044488] R10: 000055c4d58e6348 R11: 0000000000000246 R12: 0000000000000000 [ 32.051742] R13: 000055c4d58de880 R14: 0000000000000003 R15: 000000000000000e [ 32.059623] Kernel Offset: disabled [ 32.063231] Rebooting in 86400 seconds..