[....] 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[ 15.866754] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. [ 16.940868] random: sshd: uninitialized urandom read (32 bytes read) Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 17.304935] random: sshd: uninitialized urandom read (32 bytes read) [ 17.800233] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.15.202' (ECDSA) to the list of known hosts. [ 23.381938] urandom_read: 1 callbacks suppressed [ 23.381941] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 23.591234] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 23.599461] IP: [] l2tp_session_free+0x11c/0x200 [ 23.605901] PGD 1c24f1067 [ 23.608545] PUD 1c24f0067 PMD 0 [ 23.612024] [ 23.613661] Oops: 0002 [#1] PREEMPT SMP KASAN [ 23.618141] Dumping ftrace buffer: [ 23.621662] (ftrace buffer empty) [ 23.625347] Modules linked in: [ 23.628637] CPU: 0 PID: 3735 Comm: syz-executor220 Not tainted 4.9.119-g92e8704 #74 [ 23.636406] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 23.645734] task: ffff8801bf569800 task.stack: ffff8801bdae8000 [ 23.651764] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 23.660652] RSP: 0018:ffff8801bdaefca0 EFLAGS: 00010246 [ 23.666080] RAX: dffffc0000000000 RBX: ffff8801bd807680 RCX: 0000000000000000 [ 23.673342] RDX: 1ffff100395d4c30 RSI: ffffffff836bf9a1 RDI: ffff8801caea6180 [ 23.680588] RBP: ffff8801bdaefcc0 R08: ffff8801bf56a0e8 R09: 0000000000000000 [ 23.687840] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801caea6000 [ 23.695093] R13: ffff8801bd807688 R14: 0000000000000000 R15: ffffffff83015be0 [ 23.702339] FS: 0000000001d84880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 23.710540] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 23.716399] CR2: 0000000000000080 CR3: 00000001c5333000 CR4: 00000000001606f0 [ 23.723649] Stack: [ 23.725781] ffff8801bda40880 ffff8801bd807680 ffff8801bda40c50 ffff8801bda40b58 [ 23.733772] ffff8801bdaefce8 ffffffff836c72b2 ffff8801bda40cc0 ffff8801bda40880 [ 23.741766] ffffffff836c71e0 ffff8801bdaefd20 ffffffff830230f5 ffff8801bda40cc0 [ 23.749758] Call Trace: [ 23.752330] [] pppol2tp_session_destruct+0xd2/0x110 [ 23.758975] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 23.765277] [] __sk_destruct+0x55/0x590 [ 23.770891] [] ? sock_release+0x1c0/0x1c0 [ 23.776674] [] sk_destruct+0x63/0x80 [ 23.782013] [] __sk_free+0x4f/0x220 [ 23.787265] [] sk_free+0x2b/0x40 [ 23.792356] [] pppol2tp_release+0x239/0x2e0 [ 23.798326] [] sock_release+0x96/0x1c0 [ 23.803843] [] sock_close+0x16/0x20 [ 23.809100] [] __fput+0x263/0x700 [ 23.814181] [] ____fput+0x15/0x20 [ 23.819262] [] task_work_run+0x10c/0x180 [ 23.824950] [] exit_to_usermode_loop+0xfc/0x120 [ 23.831243] [] do_syscall_64+0x364/0x490 [ 23.836931] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 23.843828] 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 [ 23.870803] RIP [] l2tp_session_free+0x11c/0x200 [ 23.877311] RSP [ 23.880911] CR2: 0000000000000080 [ 23.884662] ---[ end trace 497a4d02c1f69403 ]--- [ 23.889409] Kernel panic - not syncing: Fatal exception [ 23.895100] Dumping ftrace buffer: [ 23.898621] (ftrace buffer empty) [ 23.902305] Kernel Offset: disabled [ 23.905905] Rebooting in 86400 seconds..