[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 12.991359] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. [ 13.521225] random: sshd: uninitialized urandom read (32 bytes read) [ 13.938929] random: sshd: uninitialized urandom read (32 bytes read) Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 15.135758] random: sshd: uninitialized urandom read (32 bytes read) [ 15.279344] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.3' (ECDSA) to the list of known hosts. [ 20.669071] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 20.886808] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 20.895102] IP: [] l2tp_session_free+0x11c/0x200 [ 20.901569] PGD 1c8f61067 [ 20.904234] PUD 1ca518067 PMD 0 [ 20.907727] [ 20.909353] Oops: 0002 [#1] PREEMPT SMP KASAN [ 20.913833] Dumping ftrace buffer: [ 20.917364] (ftrace buffer empty) [ 20.921052] Modules linked in: [ 20.924382] CPU: 0 PID: 3796 Comm: syz-executor452 Not tainted 4.9.113-g47bbcd6 #10 [ 20.932163] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 20.941502] task: ffff8801b7406000 task.stack: ffff8801b65e8000 [ 20.947536] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 20.956426] RSP: 0018:ffff8801b65efca0 EFLAGS: 00010246 [ 20.961863] RAX: dffffc0000000000 RBX: ffff8801cc644a00 RCX: 0000000000000000 [ 20.969122] RDX: 1ffff100398c8ba0 RSI: ffffffff836bcce1 RDI: ffff8801cc645d00 [ 20.976374] RBP: ffff8801b65efcc0 R08: ffff8801b74068e8 R09: 0000000000000000 [ 20.983652] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801cc645b80 [ 20.990914] R13: ffff8801cc644a08 R14: 0000000000000000 R15: ffffffff83013be0 [ 20.998162] FS: 00000000024ee880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 21.006379] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 21.012237] CR2: 0000000000000080 CR3: 00000001c8025000 CR4: 00000000001606f0 [ 21.019488] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 21.026750] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 21.033999] Stack: [ 21.036156] ffff8801b6581980 ffff8801cc644a00 ffff8801b6581d50 ffff8801b6581c58 [ 21.044167] ffff8801b65efce8 ffffffff836c45f2 ffff8801b6581dc0 ffff8801b6581980 [ 21.052191] ffffffff836c4520 ffff8801b65efd20 ffffffff83021095 ffff8801b6581dc0 [ 21.060206] Call Trace: [ 21.062796] [] pppol2tp_session_destruct+0xd2/0x110 [ 21.069451] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 21.075769] [] __sk_destruct+0x55/0x590 [ 21.081383] [] ? sock_release+0x1c0/0x1c0 [ 21.087160] [] sk_destruct+0x63/0x80 [ 21.092501] [] __sk_free+0x4f/0x220 [ 21.097765] [] sk_free+0x2b/0x40 [ 21.102770] [] pppol2tp_release+0x239/0x2e0 [ 21.108722] [] sock_release+0x96/0x1c0 [ 21.114236] [] sock_close+0x16/0x20 [ 21.119501] [] __fput+0x263/0x700 [ 21.124581] [] ____fput+0x15/0x20 [ 21.129685] [] task_work_run+0x10c/0x180 [ 21.135391] [] exit_to_usermode_loop+0xfc/0x120 [ 21.141692] [] do_syscall_64+0x364/0x490 [ 21.147386] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 21.154287] 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 [ 21.181480] RIP [] l2tp_session_free+0x11c/0x200 [ 21.188012] RSP [ 21.191634] CR2: 0000000000000080 [ 21.196302] ---[ end trace 957880a12145db25 ]--- [ 21.201092] Kernel panic - not syncing: Fatal exception [ 21.206972] Dumping ftrace buffer: [ 21.210503] (ftrace buffer empty) [ 21.214197] Kernel Offset: disabled [ 21.217817] Rebooting in 86400 seconds..