[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.070557] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. [ 13.888705] random: sshd: uninitialized urandom read (32 bytes read) Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 14.292917] random: sshd: uninitialized urandom read (32 bytes read) [ 14.797788] random: sshd: uninitialized urandom read (32 bytes read) [ 15.284784] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.34' (ECDSA) to the list of known hosts. [ 20.808551] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 20.994362] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 21.002600] IP: [] l2tp_session_free+0x11c/0x200 [ 21.009040] PGD 1bc744067 [ 21.011685] PUD 1c5af8067 PMD 0 [ 21.015176] [ 21.016797] Oops: 0002 [#1] PREEMPT SMP KASAN [ 21.021265] Dumping ftrace buffer: [ 21.024779] (ftrace buffer empty) [ 21.028472] Modules linked in: [ 21.031762] CPU: 0 PID: 3778 Comm: syz-executor454 Not tainted 4.9.124-g09eb2ba #83 [ 21.039528] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 21.048856] task: ffff8801bbf44800 task.stack: ffff8801b9f90000 [ 21.054885] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 21.063733] RSP: 0018:ffff8801b9f97c98 EFLAGS: 00010246 [ 21.069152] RAX: dffffc0000000000 RBX: ffff8801ca8a8a00 RCX: 0000000000000000 [ 21.076397] RDX: 1ffff1003740b3a0 RSI: ffffffff836c4711 RDI: ffff8801ba059d00 [ 21.083641] RBP: ffff8801b9f97cb8 R08: ffff8801bbf450e8 R09: 0000000000000000 [ 21.090885] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801ba059b80 [ 21.098138] R13: ffff8801ca8a8a08 R14: 0000000000000000 R15: 0000000000000000 [ 21.105384] FS: 00000000018da880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 21.113601] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 21.119460] CR2: 0000000000000080 CR3: 00000001c58c7000 CR4: 00000000001606f0 [ 21.126722] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 21.133969] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 21.141213] Stack: [ 21.143354] ffff8801b9e8dd80 ffff8801ca8a8a00 ffff8801b9e8e150 ffff8801b9e8e058 [ 21.151347] ffff8801b9f97ce0 ffffffff836cc022 ffff8801b9e8e1c0 ffff8801b9e8dd80 [ 21.159340] ffffffff836cbf50 ffff8801b9f97d18 ffffffff830281f5 ffff8801b9e8e1c0 [ 21.167348] Call Trace: [ 21.169931] [] pppol2tp_session_destruct+0xd2/0x110 [ 21.176570] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 21.182892] [] __sk_destruct+0x55/0x590 [ 21.188489] [] sk_destruct+0x63/0x80 [ 21.193824] [] __sk_free+0x4f/0x220 [ 21.199072] [] sk_free+0x2b/0x40 [ 21.204066] [] pppol2tp_release+0x239/0x2e0 [ 21.210022] [] __sock_release+0xd7/0x260 [ 21.215708] [] ? __sock_release+0x260/0x260 [ 21.221652] [] sock_close+0x19/0x20 [ 21.226912] [] __fput+0x263/0x700 [ 21.231997] [] ____fput+0x15/0x20 [ 21.237075] [] task_work_run+0x10c/0x180 [ 21.242759] [] exit_to_usermode_loop+0xfc/0x120 [ 21.249053] [] do_syscall_64+0x364/0x490 [ 21.254737] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 21.261631] 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 a5 c5 c9 fd 4c 89 ea 48 b8 00 [ 21.288463] RIP [] l2tp_session_free+0x11c/0x200 [ 21.294972] RSP [ 21.298576] CR2: 0000000000000080 [ 21.302583] ---[ end trace da6a0124ca9efea5 ]--- [ 21.307359] Kernel panic - not syncing: Fatal exception [ 21.313022] Dumping ftrace buffer: [ 21.316541] (ftrace buffer empty) [ 21.320222] Kernel Offset: disabled [ 21.323845] Rebooting in 86400 seconds..