[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.419355] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 15.082132] random: sshd: uninitialized urandom read (32 bytes read) [ 15.575668] random: sshd: uninitialized urandom read (32 bytes read) [ 16.548196] random: sshd: uninitialized urandom read (32 bytes read) [ 16.676261] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.46' (ECDSA) to the list of known hosts. [ 22.109201] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 22.316242] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 22.324458] IP: [] l2tp_session_free+0x11c/0x200 [ 22.330888] PGD 1d928e067 [ 22.333528] PUD 1d928d067 PMD 0 [ 22.337002] [ 22.338622] Oops: 0002 [#1] PREEMPT SMP KASAN [ 22.343089] Dumping ftrace buffer: [ 22.346599] (ftrace buffer empty) [ 22.350285] Modules linked in: [ 22.353566] CPU: 1 PID: 3791 Comm: syz-executor416 Not tainted 4.9.113-g47bbcd6 #62 [ 22.361327] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 22.370653] task: ffff8801ca664800 task.stack: ffff8801d8c18000 [ 22.376677] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 22.385520] RSP: 0018:ffff8801d8c1fca0 EFLAGS: 00010246 [ 22.390953] RAX: dffffc0000000000 RBX: ffff8801b6e88500 RCX: 0000000000000000 [ 22.398195] RDX: 1ffff10036d97660 RSI: ffffffff836bcce1 RDI: ffff8801b6cbb300 [ 22.405435] RBP: ffff8801d8c1fcc0 R08: ffff8801ca6650e8 R09: 0000000000000000 [ 22.412677] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b6cbb180 [ 22.419920] R13: ffff8801b6e88508 R14: 0000000000000000 R15: ffffffff83013be0 [ 22.427162] FS: 00000000022a5880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 22.435359] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 22.441209] CR2: 0000000000000080 CR3: 00000001c41b1000 CR4: 00000000001606f0 [ 22.448460] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 22.455712] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 22.462956] Stack: [ 22.465083] ffff8801b8696e80 ffff8801b6e88500 ffff8801b8697250 ffff8801b8697158 [ 22.473069] ffff8801d8c1fce8 ffffffff836c45f2 ffff8801b86972c0 ffff8801b8696e80 [ 22.481045] ffffffff836c4520 ffff8801d8c1fd20 ffffffff83021095 ffff8801b86972c0 [ 22.489032] Call Trace: [ 22.491593] [] pppol2tp_session_destruct+0xd2/0x110 [ 22.498228] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 22.504518] [] __sk_destruct+0x55/0x590 [ 22.510117] [] ? sock_release+0x1c0/0x1c0 [ 22.515886] [] sk_destruct+0x63/0x80 [ 22.521221] [] __sk_free+0x4f/0x220 [ 22.526469] [] sk_free+0x2b/0x40 [ 22.531459] [] pppol2tp_release+0x239/0x2e0 [ 22.537402] [] sock_release+0x96/0x1c0 [ 22.542908] [] sock_close+0x16/0x20 [ 22.548159] [] __fput+0x263/0x700 [ 22.553245] [] ____fput+0x15/0x20 [ 22.558319] [] task_work_run+0x10c/0x180 [ 22.564001] [] exit_to_usermode_loop+0xfc/0x120 [ 22.570290] [] do_syscall_64+0x364/0x490 [ 22.575973] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 22.582868] 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 [ 22.609602] RIP [] l2tp_session_free+0x11c/0x200 [ 22.616103] RSP [ 22.619698] CR2: 0000000000000080 [ 22.623192] ---[ end trace 0242b9701679ef3a ]--- [ 22.627943] Kernel panic - not syncing: Fatal exception [ 22.633722] Dumping ftrace buffer: [ 22.637230] (ftrace buffer empty) [ 22.640911] Kernel Offset: disabled [ 22.644509] Rebooting in 86400 seconds..