[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.386737] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 20.326986] random: sshd: uninitialized urandom read (32 bytes read) [ 20.606460] random: sshd: uninitialized urandom read (32 bytes read) [ 21.125396] random: sshd: uninitialized urandom read (32 bytes read) [ 25.924687] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.19' (ECDSA) to the list of known hosts. [ 31.413646] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 31.614046] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 31.622366] IP: [] l2tp_session_free+0x11c/0x200 [ 31.628796] PGD 1ca508067 [ 31.631579] PUD 1c5951067 PMD 0 [ 31.635061] [ 31.636682] Oops: 0002 [#1] PREEMPT SMP KASAN [ 31.641151] Dumping ftrace buffer: [ 31.644662] (ftrace buffer empty) [ 31.648353] Modules linked in: [ 31.651649] CPU: 1 PID: 3806 Comm: syz-executor309 Not tainted 4.9.122-g54068d6 #78 [ 31.659422] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 31.668754] task: ffff8801b7196000 task.stack: ffff8801b5728000 [ 31.674834] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 31.683708] RSP: 0018:ffff8801b572fca0 EFLAGS: 00010246 [ 31.689135] RAX: dffffc0000000000 RBX: ffff8801cb154280 RCX: 0000000000000000 [ 31.696462] RDX: 1ffff10036ba43a0 RSI: ffffffff836c39a1 RDI: ffff8801b5d21d00 [ 31.703715] RBP: ffff8801b572fcc0 R08: ffff8801b71968e8 R09: 0000000000000000 [ 31.710962] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b5d21b80 [ 31.718212] R13: ffff8801cb154288 R14: 0000000000000000 R15: ffffffff83019be0 [ 31.725460] FS: 0000000000d4a880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 31.734211] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 31.740069] CR2: 0000000000000080 CR3: 00000001c2656000 CR4: 00000000001606f0 [ 31.747315] Stack: [ 31.749440] ffff8801d9682200 ffff8801cb154280 ffff8801d96825d0 ffff8801d96824d8 [ 31.757509] ffff8801b572fce8 ffffffff836cb2b2 ffff8801d9682640 ffff8801d9682200 [ 31.765500] ffffffff836cb1e0 ffff8801b572fd20 ffffffff830270f5 ffff8801d9682640 [ 31.773491] Call Trace: [ 31.776061] [] pppol2tp_session_destruct+0xd2/0x110 [ 31.782708] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 31.789009] [] __sk_destruct+0x55/0x590 [ 31.794610] [] ? sock_release+0x1c0/0x1c0 [ 31.800382] [] sk_destruct+0x63/0x80 [ 31.805721] [] __sk_free+0x4f/0x220 [ 31.810976] [] sk_free+0x2b/0x40 [ 31.815967] [] pppol2tp_release+0x239/0x2e0 [ 31.821921] [] sock_release+0x96/0x1c0 [ 31.827540] [] sock_close+0x16/0x20 [ 31.832800] [] __fput+0x263/0x700 [ 31.837896] [] ____fput+0x15/0x20 [ 31.842988] [] task_work_run+0x10c/0x180 [ 31.848679] [] exit_to_usermode_loop+0xfc/0x120 [ 31.855075] [] do_syscall_64+0x364/0x490 [ 31.860765] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 31.867661] 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 95 d3 c9 fd 4c 89 ea 48 b8 00 [ 31.895218] RIP [] l2tp_session_free+0x11c/0x200 [ 31.901726] RSP [ 31.905329] CR2: 0000000000000080 [ 31.908897] ---[ end trace 3f38cfc68a26cafe ]--- [ 31.913676] Kernel panic - not syncing: Fatal exception [ 31.919348] Dumping ftrace buffer: [ 31.922871] (ftrace buffer empty) [ 31.926556] Kernel Offset: disabled [ 31.930158] Rebooting in 86400 seconds..