[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.563327] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. [ 14.629428] random: sshd: uninitialized urandom read (32 bytes read) Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 15.033863] random: sshd: uninitialized urandom read (32 bytes read) [ 15.480513] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.15.193' (ECDSA) to the list of known hosts. [ 21.028394] urandom_read: 1 callbacks suppressed [ 21.028398] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 21.241915] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 21.250151] IP: [] l2tp_session_free+0x11c/0x200 [ 21.256595] PGD 1bb555067 [ 21.259244] PUD 1c88f0067 PMD 0 [ 21.262722] [ 21.264346] Oops: 0002 [#1] PREEMPT SMP KASAN [ 21.268824] Dumping ftrace buffer: [ 21.272337] (ftrace buffer empty) [ 21.276021] Modules linked in: [ 21.279312] CPU: 1 PID: 3802 Comm: syz-executor331 Not tainted 4.9.117-g8b21e85 #19 [ 21.287077] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 21.296412] task: ffff8801b8916000 task.stack: ffff8801b5ed8000 [ 21.302439] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 21.311297] RSP: 0018:ffff8801b5edfca0 EFLAGS: 00010246 [ 21.316716] RAX: dffffc0000000000 RBX: ffff8801b5e72780 RCX: 0000000000000000 [ 21.323961] RDX: 1ffff10036bce750 RSI: ffffffff836bf8f1 RDI: ffff8801b5e73a80 [ 21.331205] RBP: ffff8801b5edfcc0 R08: ffff8801b89168e8 R09: 0000000000000000 [ 21.338448] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b5e73900 [ 21.345692] R13: ffff8801b5e72788 R14: 0000000000000000 R15: ffffffff83015be0 [ 21.352942] FS: 00000000018cd880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 21.361146] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 21.367010] CR2: 0000000000000080 CR3: 00000001c9c4c000 CR4: 00000000001606f0 [ 21.374259] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 21.381503] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 21.388747] Stack: [ 21.390869] ffff8801b7dc3300 ffff8801b5e72780 ffff8801b7dc36d0 ffff8801b7dc35d8 [ 21.398870] ffff8801b5edfce8 ffffffff836c7202 ffff8801b7dc3740 ffff8801b7dc3300 [ 21.406872] ffffffff836c7130 ffff8801b5edfd20 ffffffff83023095 ffff8801b7dc3740 [ 21.414930] Call Trace: [ 21.417512] [] pppol2tp_session_destruct+0xd2/0x110 [ 21.424161] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 21.430462] [] __sk_destruct+0x55/0x590 [ 21.436063] [] ? sock_release+0x1c0/0x1c0 [ 21.441837] [] sk_destruct+0x63/0x80 [ 21.447176] [] __sk_free+0x4f/0x220 [ 21.452434] [] sk_free+0x2b/0x40 [ 21.457436] [] pppol2tp_release+0x239/0x2e0 [ 21.463383] [] sock_release+0x96/0x1c0 [ 21.468894] [] sock_close+0x16/0x20 [ 21.474157] [] __fput+0x263/0x700 [ 21.479244] [] ____fput+0x15/0x20 [ 21.484335] [] task_work_run+0x10c/0x180 [ 21.490020] [] exit_to_usermode_loop+0xfc/0x120 [ 21.496312] [] do_syscall_64+0x364/0x490 [ 21.501998] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 21.508896] 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 41 ff 8e 80 00 00 00 74 69 e8 e5 f1 c9 fd 4c 89 ea 48 b8 00 [ 21.535801] RIP [] l2tp_session_free+0x11c/0x200 [ 21.542303] RSP [ 21.545899] CR2: 0000000000000080 [ 21.549519] ---[ end trace 811a4e282ad617c5 ]--- [ 21.554310] Kernel panic - not syncing: Fatal exception [ 21.560115] Dumping ftrace buffer: [ 21.563642] (ftrace buffer empty) [ 21.567326] Kernel Offset: disabled [ 21.570927] Rebooting in 86400 seconds..