[ OK ] Started Getty on tty2. [ OK ] Started Serial Getty on ttyS0. [ OK ] Started Getty on tty1. [ 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 '10.128.0.27' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 27.182127] [ 27.183763] ====================================================== [ 27.190052] WARNING: possible circular locking dependency detected [ 27.196346] 4.14.287-syzkaller #0 Not tainted [ 27.200836] ------------------------------------------------------ [ 27.207142] kworker/u4:2/35 is trying to acquire lock: [ 27.212397] (sk_lock-AF_INET6){+.+.}, at: [] strp_work+0x3e/0x100 [ 27.220273] [ 27.220273] but task is already holding lock: [ 27.226226] ((&strp->work)){+.+.}, at: [] process_one_work+0x6e6/0x14a0 [ 27.234622] [ 27.234622] which lock already depends on the new lock. [ 27.234622] [ 27.242914] [ 27.242914] the existing dependency chain (in reverse order) is: [ 27.250504] [ 27.250504] -> #1 ((&strp->work)){+.+.}: [ 27.256022] flush_work+0xad/0x770 [ 27.260055] __cancel_work_timer+0x321/0x460 [ 27.264957] strp_done+0x53/0xd0 [ 27.268814] kcm_ioctl+0x828/0xfb0 [ 27.272847] sock_ioctl+0x2cc/0x4c0 [ 27.276970] do_vfs_ioctl+0x75a/0xff0 [ 27.281264] SyS_ioctl+0x7f/0xb0 [ 27.285124] do_syscall_64+0x1d5/0x640 [ 27.289514] entry_SYSCALL_64_after_hwframe+0x46/0xbb [ 27.295282] [ 27.295282] -> #0 (sk_lock-AF_INET6){+.+.}: [ 27.301063] lock_acquire+0x170/0x3f0 [ 27.305377] lock_sock_nested+0xb7/0x100 [ 27.309932] strp_work+0x3e/0x100 [ 27.313886] process_one_work+0x793/0x14a0 [ 27.318627] worker_thread+0x5cc/0xff0 [ 27.323030] kthread+0x30d/0x420 [ 27.326908] ret_from_fork+0x24/0x30 [ 27.331113] [ 27.331113] other info that might help us debug this: [ 27.331113] [ 27.339233] Possible unsafe locking scenario: [ 27.339233] [ 27.345268] CPU0 CPU1 [ 27.349909] ---- ---- [ 27.354552] lock((&strp->work)); [ 27.358068] lock(sk_lock-AF_INET6); [ 27.364361] lock((&strp->work)); [ 27.370422] lock(sk_lock-AF_INET6); [ 27.374319] [ 27.374319] *** DEADLOCK *** [ 27.374319] [ 27.380351] 2 locks held by kworker/u4:2/35: [ 27.384729] #0: ("%s""kstrp"){+.+.}, at: [] process_one_work+0x6b0/0x14a0 [ 27.393380] #1: ((&strp->work)){+.+.}, at: [] process_one_work+0x6e6/0x14a0 [ 27.402205] [ 27.402205] stack backtrace: [ 27.406679] CPU: 0 PID: 35 Comm: kworker/u4:2 Not tainted 4.14.287-syzkaller #0 [ 27.414096] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/29/2022 [ 27.423450] Workqueue: kstrp strp_work [ 27.427329] Call Trace: [ 27.429911] dump_stack+0x1b2/0x281 [ 27.433517] print_circular_bug.constprop.0.cold+0x2d7/0x41e [ 27.439306] __lock_acquire+0x2e0e/0x3f20 [ 27.443548] ? __schedule+0x893/0x1de0 [ 27.447425] ? trace_hardirqs_on+0x10/0x10 [ 27.451640] ? lock_acquire+0x170/0x3f0 [ 27.455625] ? lock_sock_nested+0x98/0x100 [ 27.459849] lock_acquire+0x170/0x3f0 [ 27.463660] ? strp_work+0x3e/0x100 [ 27.467273] lock_sock_nested+0xb7/0x100 [ 27.471316] ? strp_work+0x3e/0x100 [ 27.474921] strp_work+0x3e/0x100 [ 27.478353] process_one_work+0x793/0x14a0 [ 27.482