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: [<ffffffff8681dfbe>] strp_work+0x3e/0x100
[   26.802257] 
[   26.802257] but task is already holding lock:
[   26.808198]  ((&strp->work)){+.+.}, at: [<ffffffff81364f26>] 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: [<ffffffff81364ef0>] process_one_work+0x6b0/0x14a0
[   26.975489]  #1:  ((&strp->work)){+.+.}, at: [<ffffffff81364f26>] 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