[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 12.973965] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 14.713830] random: sshd: uninitialized urandom read (32 bytes read) [ 15.054532] random: sshd: uninitialized urandom read (32 bytes read) [ 15.994893] random: sshd: uninitialized urandom read (32 bytes read) [ 16.125733] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.44' (ECDSA) to the list of known hosts. [ 21.592245] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 21.792591] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 21.800874] IP: [] l2tp_session_free+0x11c/0x200 [ 21.807371] PGD 1c99eb067 [ 21.810031] PUD 1c9b74067 PMD 0 [ 21.813556] [ 21.815190] Oops: 0002 [#1] PREEMPT SMP KASAN [ 21.819672] Dumping ftrace buffer: [ 21.823217] (ftrace buffer empty) [ 21.826919] Modules linked in: [ 21.830237] CPU: 0 PID: 3615 Comm: syz-executor188 Not tainted 4.9.113-g47bbcd6 #62 [ 21.838005] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 21.847338] task: ffff8801c6558000 task.stack: ffff8801c5b00000 [ 21.853370] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 21.862253] RSP: 0018:ffff8801c5b07ca0 EFLAGS: 00010246 [ 21.867773] RAX: dffffc0000000000 RBX: ffff8801c6e1f900 RCX: 0000000000000000 [ 21.875028] RDX: 1ffff10038b4d750 RSI: ffffffff836bcce1 RDI: ffff8801c5a6ba80 [ 21.882276] RBP: ffff8801c5b07cc0 R08: ffff8801c65588e8 R09: 0000000000000000 [ 21.889529] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801c5a6b900 [ 21.896802] R13: ffff8801c6e1f908 R14: 0000000000000000 R15: ffffffff83013be0 [ 21.904055] FS: 0000000001045880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 21.912270] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 21.918136] CR2: 0000000000000080 CR3: 00000001c77ac000 CR4: 00000000001606f0 [ 21.925389] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 21.932655] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 21.939909] Stack: [ 21.942036] ffff8801c6fa4400 ffff8801c6e1f900 ffff8801c6fa47d0 ffff8801c6fa46d8 [ 21.950078] ffff8801c5b07ce8 ffffffff836c45f2 ffff8801c6fa4840 ffff8801c6fa4400 [ 21.958127] ffffffff836c4520 ffff8801c5b07d20 ffffffff83021095 ffff8801c6fa4840 [ 21.966150] Call Trace: [ 21.968735] [] pppol2tp_session_destruct+0xd2/0x110 [ 21.976536] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 21.982836] [] __sk_destruct+0x55/0x590 [ 21.988441] [] ? sock_release+0x1c0/0x1c0 [ 21.994236] [] sk_destruct+0x63/0x80 [ 21.999581] [] __sk_free+0x4f/0x220 [ 22.004835] [] sk_free+0x2b/0x40 [ 22.009852] [] pppol2tp_release+0x239/0x2e0 [ 22.015801] [] sock_release+0x96/0x1c0 [ 22.021320] [] sock_close+0x16/0x20 [ 22.026576] [] __fput+0x263/0x700 [ 22.031665] [] ____fput+0x15/0x20 [ 22.036850] [] task_work_run+0x10c/0x180 [ 22.042551] [] exit_to_usermode_loop+0xfc/0x120 [ 22.048856] [] do_syscall_64+0x364/0x490 [ 22.054555] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 22.061475] 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 [ 22.088721] RIP [] l2tp_session_free+0x11c/0x200 [ 22.095255] RSP [ 22.098871] CR2: 0000000000000080 [ 22.102584] ---[ end trace 929f44808f89b74f ]--- [ 22.107329] Kernel panic - not syncing: Fatal exception [ 22.113390] Dumping ftrace buffer: [ 22.116919] (ftrace buffer empty) [ 22.120662] Kernel Offset: disabled [ 22.124263] Rebooting in 86400 seconds..