[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 12.572681] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 20.482849] random: sshd: uninitialized urandom read (32 bytes read) [ 20.841901] random: sshd: uninitialized urandom read (32 bytes read) [ 21.656841] random: sshd: uninitialized urandom read (32 bytes read) [ 45.791641] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.27' (ECDSA) to the list of known hosts. [ 51.216510] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 51.431589] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 51.439806] IP: [] l2tp_session_free+0x11c/0x200 [ 51.446222] PGD 1c85c5067 [ 51.448861] PUD 1c8642067 PMD 0 [ 51.452337] [ 51.453962] Oops: 0002 [#1] PREEMPT SMP KASAN [ 51.458441] Dumping ftrace buffer: [ 51.461959] (ftrace buffer empty) [ 51.465642] Modules linked in: [ 51.468941] CPU: 0 PID: 3816 Comm: syz-executor032 Not tainted 4.9.113-g90e7a90 #68 [ 51.476709] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 51.486045] task: ffff8801b86f9800 task.stack: ffff8801d9be0000 [ 51.492072] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 51.500915] RSP: 0018:ffff8801d9be7ca0 EFLAGS: 00010246 [ 51.506343] RAX: dffffc0000000000 RBX: ffff8801ca4b7900 RCX: 0000000000000000 [ 51.513587] RDX: 1ffff10039496d20 RSI: ffffffff836bdee1 RDI: ffff8801ca4b6900 [ 51.520829] RBP: ffff8801d9be7cc0 R08: ffff8801b86fa0e8 R09: 0000000000000000 [ 51.528084] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801ca4b6780 [ 51.535337] R13: ffff8801ca4b7908 R14: 0000000000000000 R15: ffffffff83014be0 [ 51.542593] FS: 00000000025bf880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 51.551360] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 51.557214] CR2: 0000000000000080 CR3: 00000001c5600000 CR4: 00000000001606f0 [ 51.564469] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 51.571711] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 51.578952] Stack: [ 51.581076] ffff8801d9769100 ffff8801ca4b7900 ffff8801d97694d0 ffff8801d97693d8 [ 51.589066] ffff8801d9be7ce8 ffffffff836c57f2 ffff8801d9769540 ffff8801d9769100 [ 51.597057] ffffffff836c5720 ffff8801d9be7d20 ffffffff83022095 ffff8801d9769540 [ 51.605049] Call Trace: [ 51.607613] [] pppol2tp_session_destruct+0xd2/0x110 [ 51.614249] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 51.620551] [] __sk_destruct+0x55/0x590 [ 51.626150] [] ? sock_release+0x1c0/0x1c0 [ 51.631920] [] sk_destruct+0x63/0x80 [ 51.637257] [] __sk_free+0x4f/0x220 [ 51.642518] [] sk_free+0x2b/0x40 [ 51.647516] [] pppol2tp_release+0x239/0x2e0 [ 51.653469] [] sock_release+0x96/0x1c0 [ 51.658977] [] sock_close+0x16/0x20 [ 51.664228] [] __fput+0x263/0x700 [ 51.669313] [] ____fput+0x15/0x20 [ 51.674388] [] task_work_run+0x10c/0x180 [ 51.680072] [] exit_to_usermode_loop+0xfc/0x120 [ 51.686362] [] do_syscall_64+0x364/0x490 [ 51.692048] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 51.698954] 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 0b ca fd 4c 89 ea 48 b8 00 [ 51.725897] RIP [] l2tp_session_free+0x11c/0x200 [ 51.732393] RSP [ 51.735997] CR2: 0000000000000080 [ 51.739524] ---[ end trace e50c8be54cdda6f0 ]--- [ 51.744269] Kernel panic - not syncing: Fatal exception [ 51.750014] Dumping ftrace buffer: [ 51.753527] (ftrace buffer empty) [ 51.757219] Kernel Offset: disabled [ 51.760816] Rebooting in 86400 seconds..