[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.093049] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. [ 14.283319] random: sshd: uninitialized urandom read (32 bytes read) Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 14.621497] random: sshd: uninitialized urandom read (32 bytes read) [ 15.072092] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.17' (ECDSA) to the list of known hosts. [ 20.909123] urandom_read: 1 callbacks suppressed [ 20.909126] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 21.117875] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 21.126112] IP: [] l2tp_session_free+0x11c/0x200 [ 21.132532] PGD 1c88f4067 [ 21.135172] PUD 1c7044067 PMD 0 [ 21.138649] [ 21.140269] Oops: 0002 [#1] PREEMPT SMP KASAN [ 21.144739] Dumping ftrace buffer: [ 21.148252] (ftrace buffer empty) [ 21.151934] Modules linked in: [ 21.155219] CPU: 1 PID: 3798 Comm: syz-executor714 Not tainted 4.9.122-g54068d6 #78 [ 21.162989] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 21.172320] task: ffff8801b7fc3000 task.stack: ffff8801b6998000 [ 21.178350] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 21.187210] RSP: 0018:ffff8801b699fca0 EFLAGS: 00010246 [ 21.192631] RAX: dffffc0000000000 RBX: ffff8801b7a70280 RCX: 0000000000000000 [ 21.199878] RDX: 1ffff10036e91fa0 RSI: ffffffff836c39a1 RDI: ffff8801b748fd00 [ 21.207122] RBP: ffff8801b699fcc0 R08: ffff8801b7fc38e8 R09: 0000000000000000 [ 21.214368] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b748fb80 [ 21.221613] R13: ffff8801b7a70288 R14: 0000000000000000 R15: ffffffff83019be0 [ 21.228861] FS: 0000000002409880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 21.237060] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 21.242915] CR2: 0000000000000080 CR3: 00000001ca0ba000 CR4: 00000000001606f0 [ 21.250161] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 21.257413] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 21.264655] Stack: [ 21.266779] ffff8801b7d3b300 ffff8801b7a70280 ffff8801b7d3b6d0 ffff8801b7d3b5d8 [ 21.274776] ffff8801b699fce8 ffffffff836cb2b2 ffff8801b7d3b740 ffff8801b7d3b300 [ 21.282790] ffffffff836cb1e0 ffff8801b699fd20 ffffffff830270f5 ffff8801b7d3b740 [ 21.290786] Call Trace: [ 21.293354] [] pppol2tp_session_destruct+0xd2/0x110 [ 21.300004] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 21.306305] [] __sk_destruct+0x55/0x590 [ 21.311915] [] ? sock_release+0x1c0/0x1c0 [ 21.317693] [] sk_destruct+0x63/0x80 [ 21.323036] [] __sk_free+0x4f/0x220 [ 21.328290] [] sk_free+0x2b/0x40 [ 21.333282] [] pppol2tp_release+0x239/0x2e0 [ 21.339231] [] sock_release+0x96/0x1c0 [ 21.344745] [] sock_close+0x16/0x20 [ 21.350000] [] __fput+0x263/0x700 [ 21.355097] [] ____fput+0x15/0x20 [ 21.360178] [] task_work_run+0x10c/0x180 [ 21.365867] [] exit_to_usermode_loop+0xfc/0x120 [ 21.372159] [] do_syscall_64+0x364/0x490 [ 21.377847] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 21.384745] 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 95 d3 c9 fd 4c 89 ea 48 b8 00 [ 21.411591] RIP [] l2tp_session_free+0x11c/0x200 [ 21.418094] RSP [ 21.421694] CR2: 0000000000000080 [ 21.425233] ---[ end trace 0ad5514099785d6e ]--- [ 21.429995] Kernel panic - not syncing: Fatal exception [ 21.435686] Dumping ftrace buffer: [ 21.439207] (ftrace buffer empty) [ 21.442889] Kernel Offset: disabled [ 21.446494] Rebooting in 86400 seconds..