[....] Starting periodic command scheduler: cron[?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 12.666811] 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: [ 17.846700] random: sshd: uninitialized urandom read (32 bytes read) [ 18.041638] random: sshd: uninitialized urandom read (32 bytes read) [ 18.566292] random: sshd: uninitialized urandom read (32 bytes read) [ 34.157811] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.39' (ECDSA) to the list of known hosts. [ 39.570324] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 39.786268] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 39.794490] IP: [<ffffffff836bf91c>] l2tp_session_free+0x11c/0x200 [ 39.800901] PGD 1c6803067 [ 39.803539] PUD 1c82e1067 PMD 0 [ 39.807014] [ 39.808631] Oops: 0002 [#1] PREEMPT SMP KASAN [ 39.813095] Dumping ftrace buffer: [ 39.816604] (ftrace buffer empty) [ 39.820298] Modules linked in: [ 39.823574] CPU: 0 PID: 3812 Comm: syz-executor267 Not tainted 4.9.117-g8b21e85 #71 [ 39.831336] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 39.840661] task: ffff8801b7929800 task.stack: ffff8801b6ed8000 [ 39.846687] RIP: 0010:[<ffffffff836bf91c>] [<ffffffff836bf91c>] l2tp_session_free+0x11c/0x200 [ 39.855527] RSP: 0018:ffff8801b6edfca0 EFLAGS: 00010246 [ 39.860945] RAX: dffffc0000000000 RBX: ffff8801b6a72c80 RCX: 0000000000000000 [ 39.868187] RDX: 1ffff10036d116b0 RSI: ffffffff836bf8f1 RDI: ffff8801b688b580 [ 39.875426] RBP: ffff8801b6edfcc0 R08: ffff8801b792a0e8 R09: 0000000000000000 [ 39.882667] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b688b400 [ 39.889905] R13: ffff8801b6a72c88 R14: 0000000000000000 R15: ffffffff83015be0 [ 39.897150] FS: 0000000002331880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 39.905358] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 39.911208] CR2: 0000000000000080 CR3: 00000001c8172000 CR4: 00000000001606f0 [ 39.918450] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 39.925693] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 39.932930] Stack: [ 39.935049] ffff8801b6a7c400 ffff8801b6a72c80 ffff8801b6a7c7d0 ffff8801b6a7c6d8 [ 39.943193] ffff8801b6edfce8 ffffffff836c7202 ffff8801b6a7c840 ffff8801b6a7c400 [ 39.951175] ffffffff836c7130 ffff8801b6edfd20 ffffffff83023095 ffff8801b6a7c840 [ 39.959161] Call Trace: [ 39.961723] [<ffffffff836c7202>] pppol2tp_session_destruct+0xd2/0x110 [ 39.968359] [<ffffffff836c7130>] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 39.974651] [<ffffffff83023095>] __sk_destruct+0x55/0x590 [ 39.980267] [<ffffffff83015be0>] ? sock_release+0x1c0/0x1c0 [ 39.986036] [<ffffffff8302ab23>] sk_destruct+0x63/0x80 [ 39.991371] [<ffffffff8302ab8f>] __sk_free+0x4f/0x220 [ 39.996621] [<ffffffff8302ad8b>] sk_free+0x2b/0x40 [ 40.001609] [<ffffffff836ca509>] pppol2tp_release+0x239/0x2e0 [ 40.007551] [<ffffffff83015ab6>] sock_release+0x96/0x1c0 [ 40.013060] [<ffffffff83015bf6>] sock_close+0x16/0x20 [ 40.018310] [<ffffffff81578693>] __fput+0x263/0x700 [ 40.023385] [<ffffffff81578bb5>] ____fput+0x15/0x20 [ 40.028472] [<ffffffff8119838c>] task_work_run+0x10c/0x180 [ 40.034170] [<ffffffff8100559c>] exit_to_usermode_loop+0xfc/0x120 [ 40.040459] [<ffffffff810064d4>] do_syscall_64+0x364/0x490 [ 40.046140] [<ffffffff839fcc13>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 40.053036] 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 e5 f1 c9 fd 4c 89 ea 48 b8 00 [ 40.079791] RIP [<ffffffff836bf91c>] l2tp_session_free+0x11c/0x200 [ 40.086301] RSP <ffff8801b6edfca0> [ 40.089894] CR2: 0000000000000080 [ 40.093733] ---[ end trace 5e53cfbe4b115886 ]--- [ 40.098486] Kernel panic - not syncing: Fatal exception [ 40.104141] Dumping ftrace buffer: [ 40.107652] (ftrace buffer empty) [ 40.111331] Kernel Offset: disabled [ 40.114931] Rebooting in 86400 seconds..