[....] 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[ 15.494870] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 19.338369] random: sshd: uninitialized urandom read (32 bytes read) [ 19.670457] random: sshd: uninitialized urandom read (32 bytes read) [ 20.158019] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.44' (ECDSA) to the list of known hosts. [ 25.758501] urandom_read: 1 callbacks suppressed [ 25.758505] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 25.943678] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 25.952000] IP: [] l2tp_session_free+0x11c/0x200 [ 25.958433] PGD 1cb447067 [ 25.961111] PUD 1c60d5067 PMD 0 [ 25.964593] [ 25.966214] Oops: 0002 [#1] PREEMPT SMP KASAN [ 25.970682] Dumping ftrace buffer: [ 25.974206] (ftrace buffer empty) [ 25.977894] Modules linked in: [ 25.981181] CPU: 0 PID: 3795 Comm: syz-executor538 Not tainted 4.9.122-g54068d6 #26 [ 25.988959] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 25.998417] task: ffff8801b95f0000 task.stack: ffff8801b6e78000 [ 26.004507] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 26.013369] RSP: 0018:ffff8801b6e7fca0 EFLAGS: 00010246 [ 26.018794] RAX: dffffc0000000000 RBX: ffff8801c8c54000 RCX: 0000000000000000 [ 26.026048] RDX: 1ffff100393dc970 RSI: ffffffff836c39a1 RDI: ffff8801c9ee4b80 [ 26.033303] RBP: ffff8801b6e7fcc0 R08: ffff8801b95f08e8 R09: 0000000000000000 [ 26.040552] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801c9ee4a00 [ 26.047799] R13: ffff8801c8c54008 R14: 0000000000000000 R15: ffffffff83019be0 [ 26.055163] FS: 0000000000c25880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 26.063365] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 26.069223] CR2: 0000000000000080 CR3: 00000001ca856000 CR4: 00000000001606f0 [ 26.076480] Stack: [ 26.078605] ffff8801b6f72200 ffff8801c8c54000 ffff8801b6f725d0 ffff8801b6f724d8 [ 26.086689] ffff8801b6e7fce8 ffffffff836cb2b2 ffff8801b6f72640 ffff8801b6f72200 [ 26.094733] ffffffff836cb1e0 ffff8801b6e7fd20 ffffffff830270f5 ffff8801b6f72640 [ 26.102735] Call Trace: [ 26.105314] [] pppol2tp_session_destruct+0xd2/0x110 [ 26.111967] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 26.118363] [] __sk_destruct+0x55/0x590 [ 26.123970] [] ? sock_release+0x1c0/0x1c0 [ 26.129748] [] sk_destruct+0x63/0x80 [ 26.135111] [] __sk_free+0x4f/0x220 [ 26.140368] [] sk_free+0x2b/0x40 [ 26.145362] [] pppol2tp_release+0x239/0x2e0 [ 26.151310] [] sock_release+0x96/0x1c0 [ 26.156839] [] sock_close+0x16/0x20 [ 26.162101] [] __fput+0x263/0x700 [ 26.167184] [] ____fput+0x15/0x20 [ 26.172272] [] task_work_run+0x10c/0x180 [ 26.177981] [] exit_to_usermode_loop+0xfc/0x120 [ 26.184278] [] do_syscall_64+0x364/0x490 [ 26.189966] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 26.196866] 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 [ 26.224032] RIP [] l2tp_session_free+0x11c/0x200 [ 26.230545] RSP [ 26.234156] CR2: 0000000000000080 [ 26.238103] ---[ end trace 9bfa3270b05116e0 ]--- [ 26.242882] Kernel panic - not syncing: Fatal exception [ 26.248626] Dumping ftrace buffer: [ 26.252149] (ftrace buffer empty) [ 26.255837] Kernel Offset: disabled [ 26.259443] Rebooting in 86400 seconds..