[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 12.390322] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 15.085260] random: sshd: uninitialized urandom read (32 bytes read) [ 15.389982] random: sshd: uninitialized urandom read (32 bytes read) [ 15.872769] random: sshd: uninitialized urandom read (32 bytes read) [ 16.592532] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.21' (ECDSA) to the list of known hosts. [ 22.025403] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 22.234484] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 22.242729] IP: [] l2tp_session_free+0x11c/0x200 [ 22.249145] PGD 1cb277067 [ 22.251785] PUD 1c9dc4067 PMD 0 [ 22.255260] [ 22.256877] Oops: 0002 [#1] PREEMPT SMP KASAN [ 22.261344] Dumping ftrace buffer: [ 22.264852] (ftrace buffer empty) [ 22.268534] Modules linked in: [ 22.271814] CPU: 0 PID: 3674 Comm: syz-executor263 Not tainted 4.9.117-g8b21e85 #19 [ 22.279577] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 22.288901] task: ffff8801c40a1800 task.stack: ffff8801c2be0000 [ 22.294932] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 22.303772] RSP: 0018:ffff8801c2be7ca0 EFLAGS: 00010246 [ 22.309189] RAX: dffffc0000000000 RBX: ffff8801ca553900 RCX: 0000000000000000 [ 22.316450] RDX: 1ffff100385f1300 RSI: ffffffff836bf8f1 RDI: ffff8801c2f89800 [ 22.323695] RBP: ffff8801c2be7cc0 R08: ffff8801c40a20e8 R09: 0000000000000000 [ 22.330937] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801c2f89680 [ 22.338178] R13: ffff8801ca553908 R14: 0000000000000000 R15: ffffffff83015be0 [ 22.345421] FS: 000000000256a880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 22.353618] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 22.359471] CR2: 0000000000000080 CR3: 00000001c9c9d000 CR4: 00000000001606f0 [ 22.366715] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 22.373972] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 22.381213] Stack: [ 22.383333] ffff8801c24d9980 ffff8801ca553900 ffff8801c24d9d50 ffff8801c24d9c58 [ 22.391337] ffff8801c2be7ce8 ffffffff836c7202 ffff8801c24d9dc0 ffff8801c24d9980 [ 22.399322] ffffffff836c7130 ffff8801c2be7d20 ffffffff83023095 ffff8801c24d9dc0 [ 22.407344] Call Trace: [ 22.409903] [] pppol2tp_session_destruct+0xd2/0x110 [ 22.416552] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 22.422844] [] __sk_destruct+0x55/0x590 [ 22.428440] [] ? sock_release+0x1c0/0x1c0 [ 22.434227] [] sk_destruct+0x63/0x80 [ 22.439560] [] __sk_free+0x4f/0x220 [ 22.444807] [] sk_free+0x2b/0x40 [ 22.449793] [] pppol2tp_release+0x239/0x2e0 [ 22.455734] [] sock_release+0x96/0x1c0 [ 22.461239] [] sock_close+0x16/0x20 [ 22.466497] [] __fput+0x263/0x700 [ 22.471575] [] ____fput+0x15/0x20 [ 22.476661] [] task_work_run+0x10c/0x180 [ 22.482375] [] exit_to_usermode_loop+0xfc/0x120 [ 22.488664] [] do_syscall_64+0x364/0x490 [ 22.494346] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 22.501240] 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 e5 f1 c9 fd 4c 89 ea 48 b8 00 [ 22.528126] RIP [] l2tp_session_free+0x11c/0x200 [ 22.534623] RSP [ 22.538232] CR2: 0000000000000080 [ 22.541856] ---[ end trace 94b41722533b5da7 ]--- [ 22.546617] Kernel panic - not syncing: Fatal exception [ 22.552234] Dumping ftrace buffer: [ 22.555747] (ftrace buffer empty) [ 22.559429] Kernel Offset: disabled [ 22.563025] Rebooting in 86400 seconds..