[....] 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[ 13.649622] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 19.316069] random: sshd: uninitialized urandom read (32 bytes read) [ 19.655842] random: sshd: uninitialized urandom read (32 bytes read) [ 20.137860] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.15.194' (ECDSA) to the list of known hosts. [ 25.686609] urandom_read: 1 callbacks suppressed [ 25.686612] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 25.895177] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 25.903619] IP: [] l2tp_session_free+0x11c/0x200 [ 25.910067] PGD 1c8a91067 [ 25.912795] PUD 1c8b2e067 PMD 0 [ 25.916283] [ 25.917905] Oops: 0002 [#1] PREEMPT SMP KASAN [ 25.922380] Dumping ftrace buffer: [ 25.925898] (ftrace buffer empty) [ 25.929585] Modules linked in: [ 25.932874] CPU: 0 PID: 3804 Comm: syz-executor953 Not tainted 4.9.119-g9dc978d #23 [ 25.940642] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 25.949973] task: ffff8801b6fab000 task.stack: ffff8801b5ae0000 [ 25.956141] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 25.964999] RSP: 0018:ffff8801b5ae7ca0 EFLAGS: 00010246 [ 25.970434] RAX: dffffc0000000000 RBX: ffff8801b5a14c80 RCX: 0000000000000000 [ 25.977755] RDX: 1ffff1003965b4d0 RSI: ffffffff836bf9a1 RDI: ffff8801cb2da680 [ 25.985010] RBP: ffff8801b5ae7cc0 R08: ffff8801b6fab8e8 R09: 0000000000000000 [ 25.992258] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801cb2da500 [ 25.999584] R13: ffff8801b5a14c88 R14: 0000000000000000 R15: ffffffff83015be0 [ 26.006848] FS: 00000000008bd880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 26.015069] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 26.020940] CR2: 0000000000000080 CR3: 00000001ca81e000 CR4: 00000000001606f0 [ 26.028192] Stack: [ 26.030365] ffff8801b586c400 ffff8801b5a14c80 ffff8801b586c7d0 ffff8801b586c6d8 [ 26.038392] ffff8801b5ae7ce8 ffffffff836c72b2 ffff8801b586c840 ffff8801b586c400 [ 26.046389] ffffffff836c71e0 ffff8801b5ae7d20 ffffffff830230f5 ffff8801b586c840 [ 26.054446] Call Trace: [ 26.057029] [] pppol2tp_session_destruct+0xd2/0x110 [ 26.063676] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 26.070121] [] __sk_destruct+0x55/0x590 [ 26.075725] [] ? sock_release+0x1c0/0x1c0 [ 26.081766] [] sk_destruct+0x63/0x80 [ 26.087124] [] __sk_free+0x4f/0x220 [ 26.092378] [] sk_free+0x2b/0x40 [ 26.097402] [] pppol2tp_release+0x239/0x2e0 [ 26.103359] [] sock_release+0x96/0x1c0 [ 26.108875] [] sock_close+0x16/0x20 [ 26.114263] [] __fput+0x263/0x700 [ 26.119348] [] ____fput+0x15/0x20 [ 26.124437] [] task_work_run+0x10c/0x180 [ 26.130124] [] exit_to_usermode_loop+0xfc/0x120 [ 26.136427] [] do_syscall_64+0x364/0x490 [ 26.142130] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 26.149030] 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 f5 f0 c9 fd 4c 89 ea 48 b8 00 [ 26.176034] RIP [] l2tp_session_free+0x11c/0x200 [ 26.182539] RSP [ 26.186184] CR2: 0000000000000080 [ 26.190557] ---[ end trace 9e313e4be37bd123 ]--- [ 26.195353] Kernel panic - not syncing: Fatal exception [ 26.200971] Dumping ftrace buffer: [ 26.204490] (ftrace buffer empty) [ 26.208177] Kernel Offset: disabled [ 26.211784] Rebooting in 86400 seconds..