[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 12.678561] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 18.958083] random: sshd: uninitialized urandom read (32 bytes read) [ 19.310064] random: sshd: uninitialized urandom read (32 bytes read) [ 19.829265] random: sshd: uninitialized urandom read (32 bytes read) [ 19.971873] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.22' (ECDSA) to the list of known hosts. [ 25.416260] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 25.623377] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 25.631613] IP: [] l2tp_session_free+0x11c/0x200 [ 25.638029] PGD 1cb375067 [ 25.640666] PUD 1c8096067 PMD 0 [ 25.644145] [ 25.645761] Oops: 0002 [#1] PREEMPT SMP KASAN [ 25.650230] Dumping ftrace buffer: [ 25.653769] (ftrace buffer empty) [ 25.657451] Modules linked in: [ 25.660739] CPU: 0 PID: 3597 Comm: syz-executor311 Not tainted 4.9.117-g8b21e85 #19 [ 25.668503] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 25.677832] task: ffff8801c7bdb000 task.stack: ffff8801c7b18000 [ 25.683862] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 25.692714] RSP: 0018:ffff8801c7b1fca0 EFLAGS: 00010246 [ 25.698134] RAX: dffffc0000000000 RBX: ffff8801c6ebbb80 RCX: 0000000000000000 [ 25.705374] RDX: 1ffff10038e80b50 RSI: ffffffff836bf8f1 RDI: ffff8801c7405a80 [ 25.712703] RBP: ffff8801c7b1fcc0 R08: ffff8801c7bdb8e8 R09: 0000000000000000 [ 25.720033] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801c7405900 [ 25.727278] R13: ffff8801c6ebbb88 R14: 0000000000000000 R15: ffffffff83015be0 [ 25.734523] FS: 0000000000cb0880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 25.742722] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 25.748594] CR2: 0000000000000080 CR3: 00000001ca09f000 CR4: 00000000001606f0 [ 25.755845] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 25.763090] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 25.770337] Stack: [ 25.772458] ffff8801c6812200 ffff8801c6ebbb80 ffff8801c68125d0 ffff8801c68124d8 [ 25.780435] ffff8801c7b1fce8 ffffffff836c7202 ffff8801c6812640 ffff8801c6812200 [ 25.788412] ffffffff836c7130 ffff8801c7b1fd20 ffffffff83023095 ffff8801c6812640 [ 25.796428] Call Trace: [ 25.798995] [] pppol2tp_session_destruct+0xd2/0x110 [ 25.805632] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 25.811936] [] __sk_destruct+0x55/0x590 [ 25.817537] [] ? sock_release+0x1c0/0x1c0 [ 25.823306] [] sk_destruct+0x63/0x80 [ 25.828661] [] __sk_free+0x4f/0x220 [ 25.833909] [] sk_free+0x2b/0x40 [ 25.838898] [] pppol2tp_release+0x239/0x2e0 [ 25.844839] [] sock_release+0x96/0x1c0 [ 25.850343] [] sock_close+0x16/0x20 [ 25.855600] [] __fput+0x263/0x700 [ 25.860674] [] ____fput+0x15/0x20 [ 25.865752] [] task_work_run+0x10c/0x180 [ 25.871436] [] exit_to_usermode_loop+0xfc/0x120 [ 25.877728] [] do_syscall_64+0x364/0x490 [ 25.883413] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 25.890317] 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 [ 25.917033] RIP [] l2tp_session_free+0x11c/0x200 [ 25.923538] RSP [ 25.927134] CR2: 0000000000000080 [ 25.930755] ---[ end trace f80570b24225c777 ]--- [ 25.935504] Kernel panic - not syncing: Fatal exception [ 25.941142] Dumping ftrace buffer: [ 25.944652] (ftrace buffer empty) [ 25.948335] Kernel Offset: disabled [ 25.951934] Rebooting in 86400 seconds..