Starting OpenBSD Secure Shell server... [ OK ] Started Permit User Sessions. [ OK ] Started System Logging Service. [ OK ] Found device /dev/ttyS0. [ OK ] Started getty on tty2-tty6 if dbus and logind are not available. [ OK ] Started OpenBSD Secure Shell server. [ OK ] Listening on Load/Save RF Kill Switch Status /dev/rfkill Watch. [ OK ] Started Getty on tty6. [ OK ] Started Getty on tty5. [ OK ] Started Getty on tty4. [ OK ] Started Getty on tty3. [ 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... Starting Load/Save RF Kill Switch Status... [ OK ] Started Load/Save RF Kill Switch Status. [ OK ] Started Update UTMP about System Runlevel Changes. Debian GNU/Linux 9 syzkaller ttyS0 Warning: Permanently added '10.128.0.241' (ECDSA) to the list of known hosts. executing program executing program executing program syzkaller login: [ 35.586998] Cannot find del_set index 0 as target [ 35.617303] ip6_tables: ip6tables: counters copy to user failed while replacing table [ 35.635290] [ 35.637216] ====================================================== [ 35.643971] WARNING: possible circular locking dependency detected [ 35.650742] 4.14.232-syzkaller #0 Not tainted [ 35.655643] ------------------------------------------------------ [ 35.662589] syz-executor911/7987 is trying to acquire lock: [ 35.669292] (&table[i].mutex){+.+.}, at: [] ip_set_nfnl_put+0x11a/0x310 [ 35.678777] [ 35.678777] but task is already holding lock: [ 35.685261] (&xt[i].mutex){+.+.}, at: [] xt_find_table_lock+0x38/0x3d0 [ 35.694411] [ 35.694411] which lock already depends on the new lock. [ 35.694411] [ 35.702817] [ 35.702817] the existing dependency chain (in reverse order) is: [ 35.711455] [ 35.711455] -> #1 (&xt[i].mutex){+.+.}: [ 35.718144] __mutex_lock+0xc4/0x1310 [ 35.723124] target_revfn+0x43/0x210 [ 35.727858] xt_find_revision+0x15e/0x1d0 [ 35.732623] nfnl_compat_get+0x1f7/0x870 [ 35.737681] nfnetlink_rcv_msg+0x9bb/0xc00 [ 35.743126] netlink_rcv_skb+0x125/0x390 [ 35.748158] nfnetlink_rcv+0x1ab/0x1da0 [ 35.753057] netlink_unicast+0x437/0x610 [ 35.758454] netlink_sendmsg+0x62e/0xb80 [ 35.763326] sock_sendmsg+0xb5/0x100 [ 35.767890] ___sys_sendmsg+0x6c8/0x800 [ 35.773651] __sys_sendmsg+0xa3/0x120 [ 35.778115] SyS_sendmsg+0x27/0x40 [ 35.782433] do_syscall_64+0x1d5/0x640 [ 35.787309] entry_SYSCALL_64_after_hwframe+0x46/0xbb [ 35.793158] [ 35.793158] -> #0 (&table[i].mutex){+.+.}: [ 35.799059] lock_acquire+0x170/0x3f0 [ 35.803666] __mutex_lock+0xc4/0x1310 [ 35.808001] ip_set_nfnl_put+0x11a/0x310 [ 35.813811] set_target_v1_destroy+0x100/0x150 [ 35.819614] cleanup_entry+0x232/0x310 [ 35.824196] __do_replace+0x38d/0x580 [ 35.828631] do_ip6t_set_ctl+0x256/0x3b0 [ 35.833527] nf_setsockopt+0x5f/0xb0 [ 35.837856] ipv6_setsockopt+0xc0/0x120 [ 35.842432] udpv6_setsockopt+0x45/0x80 [ 35.847958] SyS_setsockopt+0x110/0x1e0 [ 35.852629] do_syscall_64+0x1d5/0x640 [ 35.858193] entry_SYSCALL_64_after_hwframe+0x46/0xbb [ 35.865432] [ 35.865432] other info that might help us debug this: [ 35.865432] [ 35.874429] Possible unsafe locking scenario: [ 35.874429] [ 35.881481] CPU0 CPU1 [ 35.886693] ---- ---- [ 35.891362] lock(&xt[i].mutex); [ 35.895344] lock(&table[i].mutex); [ 35.902167] lock(&xt[i].mutex); [ 35.908781] lock(&table[i].mutex); [ 35.913458] [ 35.913458] *** DEADLOCK *** [ 35.913458] [ 35.920362] 1 lock held by syz-executor911/7987: [ 35.926086] #0: (&xt[i].mutex){+.+.}, at: [] xt_find_table_lock+0x38/0x3d0 [ 35.937697] [ 35.937697] stack backtrace: [ 35.944275] CPU: 1 PID: 7987 Comm: syz-executor911 Not tainted 4.14.232-syzkaller #0 [ 35.952722] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 35.962892] Call Trace: [ 35.966004] dump_stack+0x1b2/0x281 [ 35.969633] print_circular_bug.constprop.0.cold+0x2d7/0x41e [ 35.976061] __lock_acquire+0x2e0e/0x3f20 [ 35.980416] ? unwind_get_return_address+0x51/0x90 [ 35.986004] ? trace_hardirqs_on+0x10/0x10 [ 35.990704] ? _raw_spin_unlock_irqrestore+0x66/0xe0 [ 35.996795] ? __lock_acquire+0x5fc/0x3f20 [ 36.001290] lock_acquire+0x170/0x3f0 [ 36.005301] ? ip_set_nfnl_put+0x11a/0x310 [ 36.009649] ? ip_set_nfnl_put+0x11a/0x310 [ 36.014287] __mutex_lock+0xc4/0x1310 [ 36.019114] ? ip_set_nfnl_put+0x11a/0x310 [ 36.024026] ? ip_set_nfnl_put+0x11a/0x310 [ 36.029053] ? _raw_spin_unlock_irqrestore+0x66/0xe0 [ 36.034439] ? __ww_mutex_wakeup_for_backoff+0x210/0x210 [ 36.040565] ? ip_set_nfnl_put+0xe9/0x310 [ 36.044964] ? lock_acquire+0x170/0x3f0 [ 36.049670] ? lock_downgrade+0x740/0x740 [ 36.053922] ip_set_nfnl_put+0x11a/0x310 [ 36.058801] set_target_v1_destroy+0x100/0x150 [ 36.064108] ? set_target_v3_destroy+0x200/0x200 [ 36.069226] cleanup_entry+0x232/0x310 [ 36.073202] ? cpumask_next+0x30/0x40 [ 36.077487] ? compat_do_ip6t_get_ctl+0x820/0x820 [ 36.082604] __do_replace+0x38d/0x580 [ 36.087193] ? ip6t_unregister_table+0x60/0x60 [ 36.092081] do_ip6t_set_ctl+0x256/0x3b0 [ 36.096536] ? compat_do_ip6t_set_ctl+0x140/0x140 [ 36.101640] ? nf_sockopt_find.constprop.0+0x1ad/0x220 [ 36.107024] nf_setsockopt+0x5f/0xb0 [ 36.111084] ipv6_setsockopt+0xc0/0x120 [ 36.115790] udpv6_setsockopt+0x45/0x80 [ 36.120748] SyS_setsockopt+0x110/0x1e0 [ 36.124942] ? SyS_recv+0x40/0x40 [ 36.128663] ? up_read+0x17/0x30 [ 36.132150] ? __do_page_fault+0x159/0xad0 [ 36.136910] ? do_syscall_64+0x4c/0x640 [ 36.140992] ? SyS_recv+0x40/0x40 [ 36.144449] do_syscall_64+0x1d5/0x640 [ 36.148623] entry_SYSCALL_64_after_hwframe+0x46/0xbb [ 36.154696] RIP: 0033:0x440379 [ 36.159255] RSP: 002b:00007ffde7eaca78 EFLAGS: 00000246 ORIG_RAX: 0000000000000036 [ 36.168240] RAX: ffffffffffffffda RBX: 0030657267367069 RCX: 0000000000440379 [ 36.175818] RDX: 0000000000000040 RSI: 0000000000000029 RDI: 0000000000000003 executing program [ 36.183404] RBP: 0000000000000000 R08: 0000000000000400 R09: 00007ffde7eacc18 [ 36.191504] R10: 0000000020000040 R11: 0000000000000246 R12: 00007ffde7eaca8c [ 36.198832] R13: 431bde82d7b634db R14: 00000000004ae018 R15: 0000000000400488 [ 36.223336] ip6_tables: ip6tables: counters copy to user failed while replacing table executing program executing program executing program [ 36.240496] ip6_tables: ip6tables: counters copy to user failed while replacing table [ 36.256888] ip6_tables: ip6tables: counters copy to user failed while replacing table [ 36.273877] ip6_tables: ip6tables: counters copy to user failed while replacing table executing program executing program executing program [ 36.290265] ip6_tables: ip6tables: counters copy to user failed while replacing table [ 36.305391] ip6_tables: ip6tables: counters copy to user failed while replacing table [ 36.320451] ip6_tables: ip6tables: counters copy to user failed while replacing table executing program executing program executing program executing program executing program executing program executing program [ 36.337531] ip6_tables: ip6tables: counters copy to user failed while replacing table [ 36.353822] ip6_tables: ip6tables: counters copy to user failed while replacing table executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program [ 40.623882] net_ratelimit: 657 callbacks suppressed [ 40.623885] ip6_tables: ip6tables: counters copy to user failed while replacing table [ 40.644447] ip6_tables: ip6tables: counters copy to user failed while replacing table [ 40.660885] ip6_tables: ip6tables: counters copy to user failed while replacing table executing program executing program [ 40.675758] ip6_tables: ip6tables: counters copy to user failed while replacing table [ 40.692340] ip6_tables: ip6tables: counters copy to user failed while replacing table [ 40.707238] ip6_tables: ip6tables: counters copy to user failed while replacing table executing program executing program executing program executing program [ 40.725130] ip6_tables: ip6tables: counters copy to user failed while replacing table [ 40.740694] ip6_tables: ip6tables: counters copy to user failed while replacing table [ 40.757163] ip6_tables: ip6tables: counters copy to user failed while replacing table executing program executing program executing program executing program executing program executing program executing program executing program executing program [ 40.773121] ip6_tables: ip6tables: counters copy to user failed while replacing table executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program executing program [ 45.629278] net_ratelimit: 759 callbacks suppressed [ 45.629281] ip6_tables: ip6tables: counters copy to user failed while replacing table [ 45.651618] ip6_tables: ip6tables: counters copy to user failed while replacing table [ 45.667193] ip6_tables: ip6tables: counters copy to user failed while replacing table