Debian GNU/Linux 9 syzkaller ttyS0 Warning: Permanently added '10.128.0.29' (ECDSA) to the list of known hosts. executing program syzkaller login: [ 26.764168] [ 26.765802] ====================================================== [ 26.772094] WARNING: possible circular locking dependency detected [ 26.778389] 4.14.288-syzkaller #0 Not tainted [ 26.782855] ------------------------------------------------------ [ 26.789146] kworker/u4:2/26 is trying to acquire lock: [ 26.794393] (sk_lock-AF_INET6){+.+.}, at: [] strp_work+0x3e/0x100 [ 26.802257] [ 26.802257] but task is already holding lock: [ 26.808198] ((&strp->work)){+.+.}, at: [] process_one_work+0x6e6/0x14a0 [ 26.816579] [ 26.816579] which lock already depends on the new lock. [ 26.816579] [ 26.824865] [ 26.824865] the existing dependency chain (in reverse order) is: [ 26.832457] [ 26.832457] -> #1 ((&strp->work)){+.+.}: [ 26.838037] flush_work+0xad/0x770 [ 26.842072] __cancel_work_timer+0x321/0x460 [ 26.846978] strp_done+0x53/0xd0 [ 26.850837] kcm_ioctl+0x828/0xfb0 [ 26.855219] sock_ioctl+0x2cc/0x4c0 [ 26.859343] do_vfs_ioctl+0x75a/0xff0 [ 26.863637] SyS_ioctl+0x7f/0xb0 [ 26.867497] do_syscall_64+0x1d5/0x640 [ 26.871879] entry_SYSCALL_64_after_hwframe+0x46/0xbb [ 26.877557] [ 26.877557] -> #0 (sk_lock-AF_INET6){+.+.}: [ 26.883335] lock_acquire+0x170/0x3f0 [ 26.887629] lock_sock_nested+0xb7/0x100 [ 26.892184] strp_work+0x3e/0x100 [ 26.896132] process_one_work+0x793/0x14a0 [ 26.900860] worker_thread+0x5cc/0xff0 [ 26.905242] kthread+0x30d/0x420 [ 26.909116] ret_from_fork+0x24/0x30 [ 26.913321] [ 26.913321] other info that might help us debug this: [ 26.913321] [ 26.921431] Possible unsafe locking scenario: [ 26.921431] [ 26.927467] CPU0 CPU1 [ 26.932107] ---- ---- [ 26.936745] lock((&strp->work)); [ 26.940258] lock(sk_lock-AF_INET6); [ 26.946545] lock((&strp->work)); [ 26.952577] lock(sk_lock-AF_INET6); [ 26.956351] [ 26.956351] *** DEADLOCK *** [ 26.956351] [ 26.962385] 2 locks held by kworker/u4:2/26: [ 26.966812] #0: ("%s""kstrp"){+.+.}, at: [] process_one_work+0x6b0/0x14a0 [ 26.975489] #1: ((&strp->work)){+.+.}, at: [] process_one_work+0x6e6/0x14a0 [ 26.984313] [ 26.984313] stack backtrace: [ 26.988800] CPU: 1 PID: 26 Comm: kworker/u4:2 Not tainted 4.14.288-syzkaller #0 [ 26.996219] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/29/2022 [ 27.005683] Workqueue: kstrp strp_work [ 27.009578] Call Trace: [ 27.012148] dump_stack+0x1b2/0x281 [ 27.015763] print_circular_bug.constprop.0.cold+0x2d7/0x41e [ 27.021538] __lock_acquire+0x2e0e/0x3f20 [ 27.025663] ? trace_hardirqs_on+0x10/0x10 [ 27.029870] ? trace_hardirqs_on+0x10/0x10 [ 27.034081] ? lock_acquire+0x170/0x3f0 [ 27.038054] ? lock_sock_nested+0x98/0x100 [ 27.042304] lock_acquire+0x170/0x3f0 [ 27.046081] ? strp_work+0x3e/0x100 [ 27.049680] lock_sock_nested+0xb7/0x100 [ 27.053716] ? strp_work+0x3e/0x100 [ 27.057339] strp_work+0x3e/0x100 [ 27.060768] process_one_work+0x793/0x14a0 [ 27