[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c. [....] Starting periodic command scheduler: cron[?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 16.143909] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 19.488642] random: sshd: uninitialized urandom read (32 bytes read) [ 19.839076] random: sshd: uninitialized urandom read (32 bytes read) [ 20.336548] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.40' (ECDSA) to the list of known hosts. [ 25.972315] urandom_read: 1 callbacks suppressed [ 25.972318] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 26.174734] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 26.182987] IP: [<ffffffff836c39cc>] l2tp_session_free+0x11c/0x200 [ 26.189412] PGD 1caae6067 [ 26.192059] PUD 1ca997067 PMD 0 [ 26.195554] [ 26.197307] Oops: 0002 [#1] PREEMPT SMP KASAN [ 26.201777] Dumping ftrace buffer: [ 26.205305] (ftrace buffer empty) [ 26.208992] Modules linked in: [ 26.212395] CPU: 0 PID: 3781 Comm: syz-executor097 Not tainted 4.9.122-g54068d6 #26 [ 26.220162] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 26.229492] task: ffff8801bad23000 task.stack: ffff8801b88f0000 [ 26.235524] RIP: 0010:[<ffffffff836c39cc>] [<ffffffff836c39cc>] l2tp_session_free+0x11c/0x200 [ 26.244375] RSP: 0018:ffff8801b88f7ca0 EFLAGS: 00010246 [ 26.249793] RAX: dffffc0000000000 RBX: ffff8801b9c0c280 RCX: 0000000000000000 [ 26.257033] RDX: 1ffff100371039c0 RSI: ffffffff836c39a1 RDI: ffff8801b881ce00 [ 26.264287] RBP: ffff8801b88f7cc0 R08: ffff8801bad238e8 R09: 0000000000000000 [ 26.271528] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b881cc80 [ 26.278773] R13: ffff8801b9c0c288 R14: 0000000000000000 R15: ffffffff83019be0 [ 26.286123] FS: 0000000002036880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 26.294330] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 26.300184] CR2: 0000000000000080 CR3: 00000001cad64000 CR4: 00000000001606f0 [ 26.307441] Stack: [ 26.309564] ffff8801ba76cc80 ffff8801b9c0c280 ffff8801ba76d050 ffff8801ba76cf58 [ 26.314088] ffff8801b88f7ce8 [ 26.314090] ffffffff836cb2b2 ffff8801ba76d0c0 ffff8801ba76cc80[ 26.314094] ffffffff836cb1e0 [ 26.314095] ffff8801b88f7d20 ffffffff830270f5 ffff8801ba76d0c0[ 26.314100] Call Trace: [ 26.314110] [<ffffffff836cb2b2>] pppol2tp_session_destruct+0xd2/0x110 [ 26.314115] [<ffffffff836cb1e0>] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 26.314121] [<ffffffff830270f5>] __sk_destruct+0x55/0x590 [ 26.314127] [<ffffffff83019be0>] ? sock_release+0x1c0/0x1c0 [ 26.314131] [<ffffffff8302eb83>] sk_destruct+0x63/0x80 [ 26.314135] [<ffffffff8302ebef>] __sk_free+0x4f/0x220 [ 26.314138] [<ffffffff8302edeb>] sk_free+0x2b/0x40 [ 26.314150] [<ffffffff836ce5b9>] pppol2tp_release+0x239/0x2e0 [ 26.314154] [<ffffffff83019ab6>] sock_release+0x96/0x1c0 [ 26.314158] [<ffffffff83019bf6>] sock_close+0x16/0x20 [ 26.314165] [<ffffffff8157bdd3>] __fput+0x263/0x700 [ 26.314169] [<ffffffff8157c2f5>] ____fput+0x15/0x20 [ 26.314176] [<ffffffff8119a62c>] task_work_run+0x10c/0x180 [ 26.314181] [<ffffffff8100559c>] exit_to_usermode_loop+0xfc/0x120 [ 26.314185] [<ffffffff810064d4>] do_syscall_64+0x364/0x490 [ 26.314191] [<ffffffff83a00cd3>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 26.314253] Code: 49 8d bc 24 80 01 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 c6 00 00 00 4d 8b b4 24 80 01 00 00 <f0> 41 ff 8e 80 00 00 00 74 69 e8 95 d3 c9 fd 4c 89 ea 48 b8 00 [ 26.314258] RIP [<ffffffff836c39cc>] l2tp_session_free+0x11c/0x200 [ 26.314259] RSP <ffff8801b88f7ca0> [ 26.314261] CR2: 0000000000000080 [ 26.316593] ---[ end trace 16ef6be4549e8665 ]--- [ 26.316596] Kernel panic - not syncing: Fatal exception [ 26.317669] Dumping ftrace buffer: [ 26.317673] (ftrace buffer empty) [ 26.317675] Kernel Offset: disabled [ 26.483796] Rebooting in 86400 seconds..