[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 15.633163] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 19.468512] random: sshd: uninitialized urandom read (32 bytes read) [ 19.833482] random: sshd: uninitialized urandom read (32 bytes read) [ 20.316925] random: sshd: uninitialized urandom read (32 bytes read) [ 24.497084] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.21' (ECDSA) to the list of known hosts. [ 29.949331] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 30.170455] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 30.178692] IP: [] l2tp_session_free+0x11c/0x200 [ 30.185124] PGD 1c7258067 [ 30.187767] PUD 1c6066067 PMD 0 [ 30.191250] [ 30.192874] Oops: 0002 [#1] PREEMPT SMP KASAN [ 30.197347] Dumping ftrace buffer: [ 30.200862] (ftrace buffer empty) [ 30.204591] Modules linked in: [ 30.207892] CPU: 0 PID: 3789 Comm: syz-executor120 Not tainted 4.9.124-g09eb2ba #31 [ 30.215668] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 30.225004] task: ffff8801ba050000 task.stack: ffff8801b8908000 [ 30.231034] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 30.240127] RSP: 0018:ffff8801b890fc98 EFLAGS: 00010246 [ 30.245593] RAX: dffffc0000000000 RBX: ffff8801b896f180 RCX: 0000000000000000 [ 30.252844] RDX: 1ffff100371ea830 RSI: ffffffff836c4711 RDI: ffff8801b8f54180 [ 30.260140] RBP: ffff8801b890fcb8 R08: ffff8801ba0508e8 R09: 0000000000000000 [ 30.267411] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b8f54000 [ 30.274796] R13: ffff8801b896f188 R14: 0000000000000000 R15: 0000000000000000 [ 30.282066] FS: 0000000001188880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 30.290274] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 30.296132] CR2: 0000000000000080 CR3: 00000001bb67c000 CR4: 00000000001606f0 [ 30.303463] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 30.310717] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 30.317965] Stack: [ 30.320093] ffff8801b8f14c80 ffff8801b896f180 ffff8801b8f15050 ffff8801b8f14f58 [ 30.328145] ffff8801b890fce0 ffffffff836cc022 ffff8801b8f150c0 ffff8801b8f14c80 [ 30.336165] ffffffff836cbf50 ffff8801b890fd18 ffffffff830281f5 ffff8801b8f150c0 [ 30.344211] Call Trace: [ 30.346845] [] pppol2tp_session_destruct+0xd2/0x110 [ 30.353494] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 30.359799] [] __sk_destruct+0x55/0x590 [ 30.365405] [] sk_destruct+0x63/0x80 [ 30.370749] [] __sk_free+0x4f/0x220 [ 30.376003] [] sk_free+0x2b/0x40 [ 30.380995] [] pppol2tp_release+0x239/0x2e0 [ 30.386945] [] __sock_release+0xd7/0x260 [ 30.392632] [] ? __sock_release+0x260/0x260 [ 30.398661] [] sock_close+0x19/0x20 [ 30.403987] [] __fput+0x263/0x700 [ 30.409081] [] ____fput+0x15/0x20 [ 30.414164] [] task_work_run+0x10c/0x180 [ 30.419862] [] exit_to_usermode_loop+0xfc/0x120 [ 30.426214] [] do_syscall_64+0x364/0x490 [ 30.431911] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 30.438811] 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 [ 30.465802] RIP [] l2tp_session_free+0x11c/0x200 [ 30.472312] RSP [ 30.476015] CR2: 0000000000000080 [ 30.480076] ---[ end trace 3f070c010f67b077 ]--- [ 30.484860] Kernel panic - not syncing: Fatal exception [ 30.490551] Dumping ftrace buffer: [ 30.494073] (ftrace buffer empty) [ 30.497759] Kernel Offset: disabled [ 30.501361] Rebooting in 86400 seconds..