[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 16.013417] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 19.817382] random: sshd: uninitialized urandom read (32 bytes read) [ 20.100453] random: sshd: uninitialized urandom read (32 bytes read) [ 21.035972] random: sshd: uninitialized urandom read (32 bytes read) [ 21.164233] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.25' (ECDSA) to the list of known hosts. [ 26.881055] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 27.085624] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 27.093871] IP: [] l2tp_session_free+0x11c/0x200 [ 27.100307] PGD 1b7641067 [ 27.102960] PUD 1b70a6067 PMD 0 [ 27.106462] [ 27.108085] Oops: 0002 [#1] PREEMPT SMP KASAN [ 27.112557] Dumping ftrace buffer: [ 27.116081] (ftrace buffer empty) [ 27.119769] Modules linked in: [ 27.123072] CPU: 1 PID: 3803 Comm: syz-executor532 Not tainted 4.9.113-g47bbcd6 #10 [ 27.130837] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 27.140167] task: ffff8801b653c800 task.stack: ffff8801b5a78000 [ 27.146197] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 27.155069] RSP: 0018:ffff8801b5a7fca0 EFLAGS: 00010246 [ 27.160490] RAX: dffffc0000000000 RBX: ffff8801d99c5b80 RCX: 0000000000000000 [ 27.167736] RDX: 1ffff1003b338c30 RSI: ffffffff836bcce1 RDI: ffff8801d99c6180 [ 27.174983] RBP: ffff8801b5a7fcc0 R08: ffff8801b653d0e8 R09: 0000000000000000 [ 27.182226] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801d99c6000 [ 27.189482] R13: ffff8801d99c5b88 R14: 0000000000000000 R15: ffffffff83013be0 [ 27.196740] FS: 0000000000fd8880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 27.204954] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 27.210810] CR2: 0000000000000080 CR3: 00000001b66c4000 CR4: 00000000001606f0 [ 27.218056] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 27.225301] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 27.232556] Stack: [ 27.234695] ffff8801b5a61100 ffff8801d99c5b80 ffff8801b5a614d0 ffff8801b5a613d8 [ 27.242694] ffff8801b5a7fce8 ffffffff836c45f2 ffff8801b5a61540 ffff8801b5a61100 [ 27.250683] ffffffff836c4520 ffff8801b5a7fd20 ffffffff83021095 ffff8801b5a61540 [ 27.258695] Call Trace: [ 27.261272] [] pppol2tp_session_destruct+0xd2/0x110 [ 27.267925] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 27.274222] [] __sk_destruct+0x55/0x590 [ 27.279822] [] ? sock_release+0x1c0/0x1c0 [ 27.285607] [] sk_destruct+0x63/0x80 [ 27.290948] [] __sk_free+0x4f/0x220 [ 27.296204] [] sk_free+0x2b/0x40 [ 27.301205] [] pppol2tp_release+0x239/0x2e0 [ 27.307157] [] sock_release+0x96/0x1c0 [ 27.312676] [] sock_close+0x16/0x20 [ 27.317947] [] __fput+0x263/0x700 [ 27.323024] [] ____fput+0x15/0x20 [ 27.328116] [] task_work_run+0x10c/0x180 [ 27.333801] [] exit_to_usermode_loop+0xfc/0x120 [ 27.340095] [] do_syscall_64+0x364/0x490 [ 27.345786] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 27.352684] 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 [ 27.379576] RIP [] l2tp_session_free+0x11c/0x200 [ 27.386091] RSP [ 27.389698] CR2: 0000000000000080 [ 27.397867] ---[ end trace 283292ae1b6ba862 ]--- [ 27.402625] Kernel panic - not syncing: Fatal exception [ 27.408483] Dumping ftrace buffer: [ 27.411998] (ftrace buffer empty) [ 27.415700] Kernel Offset: disabled [ 27.419305] Rebooting in 86400 seconds..