[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.128961] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 26.701811] random: sshd: uninitialized urandom read (32 bytes read) [ 27.261575] random: sshd: uninitialized urandom read (32 bytes read) [ 28.052401] random: sshd: uninitialized urandom read (32 bytes read) [ 28.174977] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.21' (ECDSA) to the list of known hosts. [ 33.604336] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 33.809400] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 33.817624] IP: [] l2tp_session_free+0x11c/0x200 [ 33.824038] PGD 1c9fdd067 [ 33.826680] PUD 1c9fe2067 PMD 0 [ 33.830162] [ 33.831790] Oops: 0002 [#1] PREEMPT SMP KASAN [ 33.836260] Dumping ftrace buffer: [ 33.839770] (ftrace buffer empty) [ 33.843455] Modules linked in: [ 33.846751] CPU: 1 PID: 3671 Comm: syz-executor754 Not tainted 4.9.116-g0137ea2 #18 [ 33.854512] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 33.863846] task: ffff8801c54f9800 task.stack: ffff8801c30a8000 [ 33.869873] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 33.878726] RSP: 0018:ffff8801c30afca0 EFLAGS: 00010246 [ 33.884154] RAX: dffffc0000000000 RBX: ffff8801c38fef00 RCX: 0000000000000000 [ 33.891393] RDX: 1ffff10038651cd0 RSI: ffffffff836be8f1 RDI: ffff8801c328e680 [ 33.898635] RBP: ffff8801c30afcc0 R08: ffff8801c54fa0e8 R09: 0000000000000000 [ 33.905877] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801c328e500 [ 33.913128] R13: ffff8801c38fef08 R14: 0000000000000000 R15: ffffffff83014be0 [ 33.920372] FS: 000000000224b880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 33.928654] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 33.934506] CR2: 0000000000000080 CR3: 00000001c43e2000 CR4: 00000000001606f0 [ 33.941752] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 33.949004] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 33.956252] Stack: [ 33.958377] ffff8801c33a2200 ffff8801c38fef00 ffff8801c33a25d0 ffff8801c33a24d8 [ 33.966367] ffff8801c30afce8 ffffffff836c6202 ffff8801c33a2640 ffff8801c33a2200 [ 33.974352] ffffffff836c6130 ffff8801c30afd20 ffffffff83022095 ffff8801c33a2640 [ 33.982340] Call Trace: [ 33.984903] [] pppol2tp_session_destruct+0xd2/0x110 [ 33.991540] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 33.997840] [] __sk_destruct+0x55/0x590 [ 34.003437] [] ? sock_release+0x1c0/0x1c0 [ 34.009205] [] sk_destruct+0x63/0x80 [ 34.014543] [] __sk_free+0x4f/0x220 [ 34.019802] [] sk_free+0x2b/0x40 [ 34.024800] [] pppol2tp_release+0x239/0x2e0 [ 34.030756] [] sock_release+0x96/0x1c0 [ 34.036265] [] sock_close+0x16/0x20 [ 34.041511] [] __fput+0x263/0x700 [ 34.046588] [] ____fput+0x15/0x20 [ 34.051665] [] task_work_run+0x10c/0x180 [ 34.057356] [] exit_to_usermode_loop+0xfc/0x120 [ 34.063644] [] do_syscall_64+0x364/0x490 [ 34.069328] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 34.076220] 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 65 01 ca fd 4c 89 ea 48 b8 00 [ 34.103085] RIP [] l2tp_session_free+0x11c/0x200 [ 34.109586] RSP [ 34.113182] CR2: 0000000000000080 [ 34.116712] ---[ end trace abdfc3aeb0e25f5d ]--- [ 34.121481] Kernel panic - not syncing: Fatal exception [ 34.127234] Dumping ftrace buffer: [ 34.130747] (ftrace buffer empty) [ 34.134429] Kernel Offset: disabled [ 34.138026] Rebooting in 86400 seconds..