[ OK ] Reached target Graphical Interface. Starting Update UTMP about System Runlevel Changes... Starting Load/Save RF Kill Switch Status... [ OK ] Started Update UTMP about System Runlevel Changes. [ OK ] Started Load/Save RF Kill Switch Status. Debian GNU/Linux 9 syzkaller ttyS0 Warning: Permanently added '10.128.0.70' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 28.014508] [ 28.016152] ====================================================== [ 28.022533] WARNING: possible circular locking dependency detected [ 28.028825] 4.14.288-syzkaller #0 Not tainted [ 28.033376] ------------------------------------------------------ [ 28.039667] kworker/u4:3/1329 is trying to acquire lock: [ 28.045086] (sk_lock-AF_INET6){+.+.}, at: [] strp_work+0x3e/0x100 [ 28.052961] [ 28.052961] but task is already holding lock: [ 28.058909] ((&strp->work)){+.+.}, at: [] process_one_work+0x6e6/0x14a0 [ 28.067362] [ 28.067362] which lock already depends on the new lock. [ 28.067362] [ 28.076635] [ 28.076635] the existing dependency chain (in reverse order) is: [ 28.084233] [ 28.084233] -> #1 ((&strp->work)){+.+.}: [ 28.089757] flush_work+0xad/0x770 [ 28.093793] __cancel_work_timer+0x321/0x460 [ 28.098716] strp_done+0x53/0xd0 [ 28.102575] kcm_ioctl+0x828/0xfb0 [ 28.106607] sock_ioctl+0x2cc/0x4c0 [ 28.110726] do_vfs_ioctl+0x75a/0xff0 [ 28.115018] SyS_ioctl+0x7f/0xb0 [ 28.118880] do_syscall_64+0x1d5/0x640 [ 28.123259] entry_SYSCALL_64_after_hwframe+0x46/0xbb [ 28.128948] [ 28.128948] -> #0 (sk_lock-AF_INET6){+.+.}: [ 28.134729] lock_acquire+0x170/0x3f0 [ 28.139023] lock_sock_nested+0xb7/0x100 [ 28.143576] strp_work+0x3e/0x100 [ 28.147541] process_one_work+0x793/0x14a0 [ 28.152282] worker_thread+0x5cc/0xff0 [ 28.156666] kthread+0x30d/0x420 [ 28.160550] ret_from_fork+0x24/0x30 [ 28.164762] [ 28.164762] other info that might help us debug this: [ 28.164762] [ 28.172874] Possible unsafe locking scenario: [ 28.172874] [ 28.178900] CPU0 CPU1 [ 28.183539] ---- ---- [ 28.188180] lock((&strp->work)); [ 28.191693] lock(sk_lock-AF_INET6); [ 28.197987] lock((&strp->work)); [ 28.204019] lock(sk_lock-AF_INET6); [ 28.207794] [ 28.207794] *** DEADLOCK *** [ 28.207794] [ 28.213848] 2 locks held by kworker/u4:3/1329: [ 28.218418] #0: ("%s""kstrp"){+.+.}, at: [] process_one_work+0x6b0/0x14a0 [ 28.227078] #1: ((&strp->work)){+.+.}, at: [] process_one_work+0x6e6/0x14a0 [ 28.235985] [ 28.235985] stack backtrace: [ 28.240478] CPU: 0 PID: 1329 Comm: kworker/u4:3 Not tainted 4.14.288-syzkaller #0 [ 28.248079] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/29/2022 [ 28.257420] Workqueue: kstrp strp_work [ 28.261293] Call Trace: [ 28.263863] dump_stack+0x1b2/0x281 [ 28.267572] print_circular_bug.constprop.0.cold+0x2d7/0x41e [ 28.273358] __lock_acquire+0x2e0e/0x3f20 [ 28.277516] ? trace_hardirqs_on+0x10/0x10 [ 28.281727] ? trace_hardirqs_on+0x10/0x10 [ 28.285934] ? lock_acquire+0x170/0x3f0 [ 28.289897] ? lock_sock_nested+0x98/0x100 [ 28.294133] lock_acquire+0x170/0x3f0 [ 28.297920] ? strp_work+0x3e/0x100 [ 28.301531] lock_sock_nested+0xb7/0x100 [ 28.305569] ? strp_work+0x3e/0x100 [ 28.309170] strp_work+0x3e/0x100 [ 28.312610] process_one_work+0x793