[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 12.118269] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 28.453248] random: sshd: uninitialized urandom read (32 bytes read) [ 28.825815] random: sshd: uninitialized urandom read (32 bytes read) [ 29.516585] random: sshd: uninitialized urandom read (32 bytes read) [ 33.211891] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.14' (ECDSA) to the list of known hosts. [ 38.713453] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 38.911699] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 38.919922] IP: [] l2tp_session_free+0x11c/0x200 [ 38.926367] PGD 1c51f4067 [ 38.929009] PUD 1cad3c067 PMD 0 [ 38.932484] [ 38.934107] Oops: 0002 [#1] PREEMPT SMP KASAN [ 38.938573] Dumping ftrace buffer: [ 38.942097] (ftrace buffer empty) [ 38.945780] Modules linked in: [ 38.949068] CPU: 0 PID: 3808 Comm: syz-executor225 Not tainted 4.9.113-g8956c50 #67 [ 38.956829] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 38.966153] task: ffff8801b7d3e000 task.stack: ffff8801d8cb0000 [ 38.972190] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 38.981034] RSP: 0018:ffff8801d8cb7ca0 EFLAGS: 00010246 [ 38.986452] RAX: dffffc0000000000 RBX: ffff8801b7b6e000 RCX: 0000000000000000 [ 38.993701] RDX: 1ffff10039417570 RSI: ffffffff836bcee1 RDI: ffff8801ca0bab80 [ 39.000959] RBP: ffff8801d8cb7cc0 R08: ffff8801b7d3e8e8 R09: 0000000000000000 [ 39.008214] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801ca0baa00 [ 39.015454] R13: ffff8801b7b6e008 R14: 0000000000000000 R15: ffffffff83013be0 [ 39.022713] FS: 00000000025ad880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 39.030910] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 39.036764] CR2: 0000000000000080 CR3: 00000001baa77000 CR4: 00000000001606f0 [ 39.044016] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 39.051257] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 39.058500] Stack: [ 39.060632] ffff8801c6ed6600 ffff8801b7b6e000 ffff8801c6ed69d0 ffff8801c6ed68d8 [ 39.068607] ffff8801d8cb7ce8 ffffffff836c47f2 ffff8801c6ed6a40 ffff8801c6ed6600 [ 39.076591] ffffffff836c4720 ffff8801d8cb7d20 ffffffff83021095 ffff8801c6ed6a40 [ 39.084602] Call Trace: [ 39.087168] [] pppol2tp_session_destruct+0xd2/0x110 [ 39.093811] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 39.100101] [] __sk_destruct+0x55/0x590 [ 39.105697] [] ? sock_release+0x1c0/0x1c0 [ 39.111462] [] sk_destruct+0x63/0x80 [ 39.116795] [] __sk_free+0x4f/0x220 [ 39.122043] [] sk_free+0x2b/0x40 [ 39.127029] [] pppol2tp_release+0x239/0x2e0 [ 39.132973] [] sock_release+0x96/0x1c0 [ 39.138488] [] sock_close+0x16/0x20 [ 39.143736] [] __fput+0x263/0x700 [ 39.148817] [] ____fput+0x15/0x20 [ 39.153890] [] task_work_run+0x10c/0x180 [ 39.159572] [] exit_to_usermode_loop+0xfc/0x120 [ 39.165876] [] do_syscall_64+0x364/0x490 [ 39.171557] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 39.178449] 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 1b ca fd 4c 89 ea 48 b8 00 [ 39.205129] RIP [] l2tp_session_free+0x11c/0x200 [ 39.211622] RSP [ 39.215218] CR2: 0000000000000080 [ 39.218749] ---[ end trace 46f6391ecddcf5b1 ]--- [ 39.223492] Kernel panic - not syncing: Fatal exception [ 39.229275] Dumping ftrace buffer: [ 39.232794] (ftrace buffer empty) [ 39.236479] Kernel Offset: disabled [ 39.240081] Rebooting in 86400 seconds..