[ OK ] Started Getty on tty1. [ OK ] Reached target Login Prompts. [ OK ] Started OpenBSD Secure Shell server. [ OK ] Listening on Load/Save RF Kill Switch Status /dev/rfkill Watch. [ 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 '10.128.1.123' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 26.848735] [ 26.850375] ====================================================== [ 26.856674] WARNING: possible circular locking dependency detected [ 26.862979] 4.14.286-syzkaller #0 Not tainted [ 26.867446] ------------------------------------------------------ [ 26.873740] kworker/u4:0/5 is trying to acquire lock: [ 26.878903] (sk_lock-AF_INET6){+.+.}, at: [] strp_work+0x3e/0x100 [ 26.886773] [ 26.886773] but task is already holding lock: [ 26.892717] ((&strp->work)){+.+.}, at: [] process_one_work+0x6e6/0x14a0 [ 26.901117] [ 26.901117] which lock already depends on the new lock. [ 26.901117] [ 26.909411] [ 26.909411] the existing dependency chain (in reverse order) is: [ 26.917009] [ 26.917009] -> #1 ((&strp->work)){+.+.}: [ 26.922527] flush_work+0xad/0x770 [ 26.926559] __cancel_work_timer+0x321/0x460 [ 26.931462] strp_done+0x53/0xd0 [ 26.935322] kcm_ioctl+0x828/0xfb0 [ 26.939354] sock_ioctl+0x2cc/0x4c0 [ 26.943475] do_vfs_ioctl+0x75a/0xff0 [ 26.947769] SyS_ioctl+0x7f/0xb0 [ 26.951631] do_syscall_64+0x1d5/0x640 [ 26.956011] entry_SYSCALL_64_after_hwframe+0x46/0xbb [ 26.961714] [ 26.961714] -> #0 (sk_lock-AF_INET6){+.+.}: [ 26.967501] lock_acquire+0x170/0x3f0 [ 26.971803] lock_sock_nested+0xb7/0x100 [ 26.976363] strp_work+0x3e/0x100 [ 26.980315] process_one_work+0x793/0x14a0 [ 26.985045] worker_thread+0x5cc/0xff0 [ 26.989429] kthread+0x30d/0x420 [ 26.993290] ret_from_fork+0x24/0x30 [ 26.997491] [ 26.997491] other info that might help us debug this: [ 26.997491] [ 27.005601] Possible unsafe locking scenario: [ 27.005601] [ 27.011628] CPU0 CPU1 [ 27.016267] ---- ---- [ 27.020902] lock((&strp->work)); [ 27.024412] lock(sk_lock-AF_INET6); [ 27.030701] lock((&strp->work)); [ 27.036730] lock(sk_lock-AF_INET6); [ 27.040511] [ 27.040511] *** DEADLOCK *** [ 27.040511] [ 27.046540] 2 locks held by kworker/u4:0/5: [ 27.050829] #0: ("%s""kstrp"){+.+.}, at: [] process_one_work+0x6b0/0x14a0 [ 27.059467] #1: ((&strp->work)){+.+.}, at: [] process_one_work+0x6e6/0x14a0 [ 27.068277] [ 27.068277] stack backtrace: [ 27.072746] CPU: 0 PID: 5 Comm: kworker/u4:0 Not tainted 4.14.286-syzkaller #0 [ 27.080078] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/29/2022 [ 27.089418] Workqueue: kstrp strp_work [ 27.093278] Call Trace: [ 27.095853] dump_stack+0x1b2/0x281 [ 27.099553] print_circular_bug.constprop.0.cold+0x2d7/0x41e [ 27.105326] __lock_acquire+0x2e0e/0x3f20 [ 27.109451] ? __schedule+0x893/0x1de0 [ 27.113311] ? trace_hardirqs_on+0x10/0x10 [ 27.117522] ? lock_acquire+0x170/0x3f0 [ 27.121472] ? lock_sock_nested+0x98/0x100 [ 27.125681] lock_acquire+0x170/0x3f0 [ 27.129457] ? strp_work+0x3e/0x100 [ 27.133057] lock_sock_nested+0xb7/0x100 [ 27.137090] ? strp_work+0x3e/0x100 [ 27.140687] strp_work+0x3e/0x100 [ 27.144115] process_one_work+0x793/0x14a0 [ 27.148322] ? wo