[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 16.044698] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 23.174573] random: sshd: uninitialized urandom read (32 bytes read) [ 23.621216] random: sshd: uninitialized urandom read (32 bytes read) [ 24.645779] random: sshd: uninitialized urandom read (32 bytes read) [ 24.779808] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.26' (ECDSA) to the list of known hosts. [ 30.208847] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 30.412644] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 30.420929] IP: [] l2tp_session_free+0x11c/0x200 [ 30.427384] PGD 1bfb26067 [ 30.430038] PUD 1bfb27067 PMD 0 [ 30.433539] [ 30.435180] Oops: 0002 [#1] PREEMPT SMP KASAN [ 30.439672] Dumping ftrace buffer: [ 30.443210] (ftrace buffer empty) [ 30.446909] Modules linked in: [ 30.450390] CPU: 1 PID: 3811 Comm: syz-executor528 Not tainted 4.9.113-g47bbcd6 #62 [ 30.458177] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 30.467532] task: ffff8801b80d8000 task.stack: ffff8801d9158000 [ 30.473580] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 30.483305] RSP: 0018:ffff8801d915fca0 EFLAGS: 00010246 [ 30.488775] RAX: dffffc0000000000 RBX: ffff8801d90a4c80 RCX: 0000000000000000 [ 30.496037] RDX: 1ffff10038ebb520 RSI: ffffffff836bcce1 RDI: ffff8801c75da900 [ 30.503304] RBP: ffff8801d915fcc0 R08: ffff8801b80d88e8 R09: 0000000000000000 [ 30.510575] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801c75da780 [ 30.517839] R13: ffff8801d90a4c88 R14: 0000000000000000 R15: ffffffff83013be0 [ 30.525113] FS: 0000000002291880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 30.533348] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 30.539225] CR2: 0000000000000080 CR3: 00000001c0b65000 CR4: 00000000001606f0 [ 30.546489] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 30.553755] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 30.561033] Stack: [ 30.563169] ffff8801c1d06600 ffff8801d90a4c80 ffff8801c1d069d0 ffff8801c1d068d8 [ 30.571226] ffff8801d915fce8 ffffffff836c45f2 ffff8801c1d06a40 ffff8801c1d06600 [ 30.579319] ffffffff836c4520 ffff8801d915fd20 ffffffff83021095 ffff8801c1d06a40 [ 30.587388] Call Trace: [ 30.590001] [] pppol2tp_session_destruct+0xd2/0x110 [ 30.596691] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 30.603022] [] __sk_destruct+0x55/0x590 [ 30.608645] [] ? sock_release+0x1c0/0x1c0 [ 30.614466] [] sk_destruct+0x63/0x80 [ 30.619841] [] __sk_free+0x4f/0x220 [ 30.625112] [] sk_free+0x2b/0x40 [ 30.630133] [] pppol2tp_release+0x239/0x2e0 [ 30.636102] [] sock_release+0x96/0x1c0 [ 30.641655] [] sock_close+0x16/0x20 [ 30.646952] [] __fput+0x263/0x700 [ 30.652072] [] ____fput+0x15/0x20 [ 30.657174] [] task_work_run+0x10c/0x180 [ 30.662880] [] exit_to_usermode_loop+0xfc/0x120 [ 30.669195] [] do_syscall_64+0x364/0x490 [ 30.674899] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 30.681817] 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 [ 30.709189] RIP [] l2tp_session_free+0x11c/0x200 [ 30.715738] RSP [ 30.719356] CR2: 0000000000000080 [ 30.722958] ---[ end trace 7b7b255f2a115c18 ]--- [ 30.727741] Kernel panic - not syncing: Fatal exception [ 30.733728] Dumping ftrace buffer: [ 30.737281] (ftrace buffer empty) [ 30.740997] Kernel Offset: disabled [ 30.744628] Rebooting in 86400 seconds..