[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 12.430631] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 20.518797] random: sshd: uninitialized urandom read (32 bytes read) [ 20.777637] random: sshd: uninitialized urandom read (32 bytes read) [ 21.728204] random: sshd: uninitialized urandom read (32 bytes read) [ 21.861520] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.47' (ECDSA) to the list of known hosts. [ 27.247477] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 27.449001] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 27.457294] IP: [] l2tp_session_free+0x11c/0x200 [ 27.463737] PGD 1c02fd067 [ 27.466379] PUD 1c07d6067 PMD 0 [ 27.469868] [ 27.471489] Oops: 0002 [#1] PREEMPT SMP KASAN [ 27.475976] Dumping ftrace buffer: [ 27.479499] (ftrace buffer empty) [ 27.483182] Modules linked in: [ 27.486484] CPU: 1 PID: 3723 Comm: syz-executor748 Not tainted 4.9.113-g47bbcd6 #62 [ 27.494255] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 27.503584] task: ffff8801c0351800 task.stack: ffff8801be580000 [ 27.509624] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 27.518477] RSP: 0018:ffff8801be587ca0 EFLAGS: 00010246 [ 27.523899] RAX: dffffc0000000000 RBX: ffff8801cab24280 RCX: 0000000000000000 [ 27.531143] RDX: 1ffff10037d59030 RSI: ffffffff836bcce1 RDI: ffff8801beac8180 [ 27.538409] RBP: ffff8801be587cc0 R08: ffff8801c03520e8 R09: 0000000000000000 [ 27.545657] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801beac8000 [ 27.552907] R13: ffff8801cab24288 R14: 0000000000000000 R15: ffffffff83013be0 [ 27.560162] FS: 0000000002380880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 27.568362] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 27.574220] CR2: 0000000000000080 CR3: 00000001bfea9000 CR4: 00000000001606f0 [ 27.581489] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 27.588738] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 27.595989] Stack: [ 27.598113] ffff8801bfedee80 ffff8801cab24280 ffff8801bfedf250 ffff8801bfedf158 [ 27.606098] ffff8801be587ce8 ffffffff836c45f2 ffff8801bfedf2c0 ffff8801bfedee80 [ 27.614085] ffffffff836c4520 ffff8801be587d20 ffffffff83021095 ffff8801bfedf2c0 [ 27.622090] Call Trace: [ 27.624657] [] pppol2tp_session_destruct+0xd2/0x110 [ 27.631296] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 27.637605] [] __sk_destruct+0x55/0x590 [ 27.643203] [] ? sock_release+0x1c0/0x1c0 [ 27.648984] [] sk_destruct+0x63/0x80 [ 27.654331] [] __sk_free+0x4f/0x220 [ 27.659583] [] sk_free+0x2b/0x40 [ 27.664578] [] pppol2tp_release+0x239/0x2e0 [ 27.670536] [] sock_release+0x96/0x1c0 [ 27.676047] [] sock_close+0x16/0x20 [ 27.681299] [] __fput+0x263/0x700 [ 27.686378] [] ____fput+0x15/0x20 [ 27.691467] [] task_work_run+0x10c/0x180 [ 27.697172] [] exit_to_usermode_loop+0xfc/0x120 [ 27.703467] [] do_syscall_64+0x364/0x490 [ 27.709163] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 27.716069] 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 55 1d ca fd 4c 89 ea 48 b8 00 [ 27.743213] RIP [] l2tp_session_free+0x11c/0x200 [ 27.749722] RSP [ 27.753321] CR2: 0000000000000080 [ 27.756861] ---[ end trace 5584c23c1d02e0ce ]--- [ 27.761622] Kernel panic - not syncing: Fatal exception [ 27.767498] Dumping ftrace buffer: [ 27.771023] (ftrace buffer empty) [ 27.774708] Kernel Offset: disabled [ 27.778314] Rebooting in 86400 seconds..