[....] 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[ 13.627554] 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: [ 16.325011] random: sshd: uninitialized urandom read (32 bytes read) [ 16.538837] random: sshd: uninitialized urandom read (32 bytes read) [ 17.057015] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.4' (ECDSA) to the list of known hosts. [ 22.704314] urandom_read: 1 callbacks suppressed [ 22.704319] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 22.908607] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 22.916867] IP: [<ffffffff836c39cc>] l2tp_session_free+0x11c/0x200 [ 22.923299] PGD 1cb3f1067 [ 22.925945] PUD 1c9c83067 PMD 0 [ 22.929427] [ 22.931071] Oops: 0002 [#1] PREEMPT SMP KASAN [ 22.935543] Dumping ftrace buffer: [ 22.939058] (ftrace buffer empty) [ 22.942745] Modules linked in: [ 22.946039] CPU: 0 PID: 3791 Comm: syz-executor950 Not tainted 4.9.122-g54068d6 #78 [ 22.953813] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 22.963147] task: ffff8801ba7a3000 task.stack: ffff8801b76f8000 [ 22.969181] RIP: 0010:[<ffffffff836c39cc>] [<ffffffff836c39cc>] l2tp_session_free+0x11c/0x200 [ 22.978040] RSP: 0018:ffff8801b76ffca0 EFLAGS: 00010246 [ 22.983465] RAX: dffffc0000000000 RBX: ffff8801b77c8500 RCX: 0000000000000000 [ 22.990813] RDX: 1ffff10036eb3120 RSI: ffffffff836c39a1 RDI: ffff8801b7598900 [ 22.998085] RBP: ffff8801b76ffcc0 R08: ffff8801ba7a38e8 R09: 0000000000000000 [ 23.005339] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b7598780 [ 23.012606] R13: ffff8801b77c8508 R14: 0000000000000000 R15: ffffffff83019be0 [ 23.019855] FS: 0000000001f58880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 23.028060] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 23.033916] CR2: 0000000000000080 CR3: 00000001be279000 CR4: 00000000001606f0 [ 23.041162] Stack: [ 23.043287] ffff8801b8ea4c80 ffff8801b77c8500 ffff8801b8ea5050 ffff8801b8ea4f58 [ 23.051291] ffff8801b76ffce8 ffffffff836cb2b2 ffff8801b8ea50c0 ffff8801b8ea4c80 [ 23.059283] ffffffff836cb1e0 ffff8801b76ffd20 ffffffff830270f5 ffff8801b8ea50c0 [ 23.067321] Call Trace: [ 23.069894] [<ffffffff836cb2b2>] pppol2tp_session_destruct+0xd2/0x110 [ 23.076540] [<ffffffff836cb1e0>] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 23.082835] [<ffffffff830270f5>] __sk_destruct+0x55/0x590 [ 23.088436] [<ffffffff83019be0>] ? sock_release+0x1c0/0x1c0 [ 23.094219] [<ffffffff8302eb83>] sk_destruct+0x63/0x80 [ 23.099560] [<ffffffff8302ebef>] __sk_free+0x4f/0x220 [ 23.104816] [<ffffffff8302edeb>] sk_free+0x2b/0x40 [ 23.109850] [<ffffffff836ce5b9>] pppol2tp_release+0x239/0x2e0 [ 23.115803] [<ffffffff83019ab6>] sock_release+0x96/0x1c0 [ 23.121332] [<ffffffff83019bf6>] sock_close+0x16/0x20 [ 23.126589] [<ffffffff8157bdd3>] __fput+0x263/0x700 [ 23.131673] [<ffffffff8157c2f5>] ____fput+0x15/0x20 [ 23.136762] [<ffffffff8119a62c>] task_work_run+0x10c/0x180 [ 23.142497] [<ffffffff8100559c>] exit_to_usermode_loop+0xfc/0x120 [ 23.148840] [<ffffffff810064d4>] do_syscall_64+0x364/0x490 [ 23.154546] [<ffffffff83a00cd3>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 23.161448] 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 [ 23.188425] RIP [<ffffffff836c39cc>] l2tp_session_free+0x11c/0x200 [ 23.194944] RSP <ffff8801b76ffca0> [ 23.198578] CR2: 0000000000000080 [ 23.202579] ---[ end trace f0e31c01dadee71f ]--- [ 23.207336] Kernel panic - not syncing: Fatal exception [ 23.212980] Dumping ftrace buffer: [ 23.216499] (ftrace buffer empty) [ 23.220182] Kernel Offset: disabled [ 23.223785] Rebooting in 86400 seconds..