[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 16.120959] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 17.951270] random: sshd: uninitialized urandom read (32 bytes read) [ 18.382616] random: sshd: uninitialized urandom read (32 bytes read) [ 18.883550] random: sshd: uninitialized urandom read (32 bytes read) [ 19.033591] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.22' (ECDSA) to the list of known hosts. [ 24.684861] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 24.901550] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 24.909807] IP: [] l2tp_session_free+0x11c/0x200 [ 24.916230] PGD 1caec0067 [ 24.918878] PUD 1c93bd067 PMD 0 [ 24.922375] [ 24.924007] Oops: 0002 [#1] PREEMPT SMP KASAN [ 24.928535] Dumping ftrace buffer: [ 24.932053] (ftrace buffer empty) [ 24.935740] Modules linked in: [ 24.939031] CPU: 1 PID: 3795 Comm: syz-executor225 Not tainted 4.9.123-g8dd3fc2 #79 [ 24.946903] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 24.956234] task: ffff8801b6c38000 task.stack: ffff8801b6360000 [ 24.962266] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 24.971162] RSP: 0018:ffff8801b6367ca0 EFLAGS: 00010246 [ 24.976589] RAX: dffffc0000000000 RBX: ffff8801cbb58c80 RCX: 0000000000000000 [ 24.983878] RDX: 1ffff10036c3e030 RSI: ffffffff836c4991 RDI: ffff8801b61f0180 [ 24.991251] RBP: ffff8801b6367cc0 R08: ffff8801b6c388e8 R09: 0000000000000000 [ 24.998498] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b61f0000 [ 25.005744] R13: ffff8801cbb58c88 R14: 0000000000000000 R15: ffffffff8301abe0 [ 25.012992] FS: 0000000000e99880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 25.021193] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 25.027094] CR2: 0000000000000080 CR3: 00000001c9331000 CR4: 00000000001606f0 [ 25.034350] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 25.041600] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 25.048852] Stack: [ 25.050984] ffff8801b63a0000 ffff8801cbb58c80 ffff8801b63a03d0 ffff8801b63a02d8 [ 25.058991] ffff8801b6367ce8 ffffffff836cc2a2 ffff8801b63a0440 ffff8801b63a0000 [ 25.067003] ffffffff836cc1d0 ffff8801b6367d20 ffffffff830280f5 ffff8801b63a0440 [ 25.075084] Call Trace: [ 25.077654] [] pppol2tp_session_destruct+0xd2/0x110 [ 25.084294] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 25.090592] [] __sk_destruct+0x55/0x590 [ 25.096193] [] ? sock_release+0x1c0/0x1c0 [ 25.101966] [] sk_destruct+0x63/0x80 [ 25.107304] [] __sk_free+0x4f/0x220 [ 25.112558] [] sk_free+0x2b/0x40 [ 25.117677] [] pppol2tp_release+0x239/0x2e0 [ 25.123639] [] sock_release+0x96/0x1c0 [ 25.129156] [] sock_close+0x16/0x20 [ 25.134412] [] __fput+0x263/0x700 [ 25.139515] [] ____fput+0x15/0x20 [ 25.144594] [] task_work_run+0x10c/0x180 [ 25.150285] [] exit_to_usermode_loop+0xfc/0x120 [ 25.156678] [] do_syscall_64+0x364/0x490 [ 25.162368] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 25.169268] 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 e5 c3 c9 fd 4c 89 ea 48 b8 00 [ 25.196390] RIP [] l2tp_session_free+0x11c/0x200 [ 25.202894] RSP [ 25.206492] CR2: 0000000000000080 [ 25.210240] ---[ end trace a4529b76969892dc ]--- [ 25.215006] Kernel panic - not syncing: Fatal exception [ 25.220712] Dumping ftrace buffer: [ 25.224227] (ftrace buffer empty) [ 25.227913] Kernel Offset: disabled [ 25.231513] Rebooting in 86400 seconds..