[....] Starting periodic command scheduler: cron[?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 15.218749] 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: [ 17.285224] random: sshd: uninitialized urandom read (32 bytes read) [ 17.648437] random: sshd: uninitialized urandom read (32 bytes read) [ 18.621489] random: sshd: uninitialized urandom read (32 bytes read) [ 18.756301] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.12' (ECDSA) to the list of known hosts. [ 24.189526] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 24.389338] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 24.397566] IP: [<ffffffff836be91c>] l2tp_session_free+0x11c/0x200 [ 24.403996] PGD 1c8c0c067 [ 24.406639] PUD 1c329b067 PMD 0 [ 24.410130] [ 24.411752] Oops: 0002 [#1] PREEMPT SMP KASAN [ 24.416218] Dumping ftrace buffer: [ 24.419729] (ftrace buffer empty) [ 24.423414] Modules linked in: [ 24.426713] CPU: 1 PID: 3750 Comm: syz-executor169 Not tainted 4.9.116-g0137ea2 #18 [ 24.434479] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 24.443808] task: ffff8801bdf71800 task.stack: ffff8801bc2d0000 [ 24.449841] RIP: 0010:[<ffffffff836be91c>] [<ffffffff836be91c>] l2tp_session_free+0x11c/0x200 [ 24.458690] RSP: 0018:ffff8801bc2d7ca0 EFLAGS: 00010246 [ 24.464111] RAX: dffffc0000000000 RBX: ffff8801bd334000 RCX: 0000000000000000 [ 24.471365] RDX: 1ffff1003796e170 RSI: ffffffff836be8f1 RDI: ffff8801bcb70b80 [ 24.478626] RBP: ffff8801bc2d7cc0 R08: ffff8801bdf720e8 R09: 0000000000000000 [ 24.485869] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801bcb70a00 [ 24.493124] R13: ffff8801bd334008 R14: 0000000000000000 R15: ffffffff83014be0 [ 24.500377] FS: 0000000001f96880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 24.508577] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 24.514433] CR2: 0000000000000080 CR3: 00000001bdf5d000 CR4: 00000000001606f0 [ 24.521683] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 24.528927] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 24.536198] Stack: [ 24.538323] ffff8801bf11ee80 ffff8801bd334000 ffff8801bf11f250 ffff8801bf11f158 [ 24.546320] ffff8801bc2d7ce8 ffffffff836c6202 ffff8801bf11f2c0 ffff8801bf11ee80 [ 24.554316] ffffffff836c6130 ffff8801bc2d7d20 ffffffff83022095 ffff8801bf11f2c0 [ 24.562305] Call Trace: [ 24.564874] [<ffffffff836c6202>] pppol2tp_session_destruct+0xd2/0x110 [ 24.571518] [<ffffffff836c6130>] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 24.577810] [<ffffffff83022095>] __sk_destruct+0x55/0x590 [ 24.583407] [<ffffffff83014be0>] ? sock_release+0x1c0/0x1c0 [ 24.589182] [<ffffffff83029b23>] sk_destruct+0x63/0x80 [ 24.594521] [<ffffffff83029b8f>] __sk_free+0x4f/0x220 [ 24.599780] [<ffffffff83029d8b>] sk_free+0x2b/0x40 [ 24.604769] [<ffffffff836c9509>] pppol2tp_release+0x239/0x2e0 [ 24.610726] [<ffffffff83014ab6>] sock_release+0x96/0x1c0 [ 24.616239] [<ffffffff83014bf6>] sock_close+0x16/0x20 [ 24.621493] [<ffffffff81578453>] __fput+0x263/0x700 [ 24.626570] [<ffffffff81578975>] ____fput+0x15/0x20 [ 24.631654] [<ffffffff8119838c>] task_work_run+0x10c/0x180 [ 24.637337] [<ffffffff8100559c>] exit_to_usermode_loop+0xfc/0x120 [ 24.643641] [<ffffffff810064d4>] do_syscall_64+0x364/0x490 [ 24.649328] [<ffffffff839fbc13>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 24.656228] 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 65 01 ca fd 4c 89 ea 48 b8 00 [ 24.683134] RIP [<ffffffff836be91c>] l2tp_session_free+0x11c/0x200 [ 24.689640] RSP <ffff8801bc2d7ca0> [ 24.693239] CR2: 0000000000000080 [ 24.696801] ---[ end trace b9327249f96d8fd7 ]--- [ 24.701566] Kernel panic - not syncing: Fatal exception [ 24.707300] Dumping ftrace buffer: [ 24.710826] (ftrace buffer empty) [ 24.714512] Kernel Offset: disabled [ 24.718114] Rebooting in 86400 seconds..