[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.971338] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 18.184802] random: sshd: uninitialized urandom read (32 bytes read) [ 18.547107] random: sshd: uninitialized urandom read (32 bytes read) [ 19.096975] random: sshd: uninitialized urandom read (32 bytes read) [ 19.235570] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.24' (ECDSA) to the list of known hosts. [ 24.910799] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 25.128166] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 25.136479] IP: [] l2tp_session_free+0x11c/0x200 [ 25.142904] PGD 1bb0a9067 [ 25.145546] PUD 1bd417067 PMD 0 [ 25.149024] [ 25.150673] Oops: 0002 [#1] PREEMPT SMP KASAN [ 25.155155] Dumping ftrace buffer: [ 25.158675] (ftrace buffer empty) [ 25.162377] Modules linked in: [ 25.165722] CPU: 1 PID: 3797 Comm: syz-executor057 Not tainted 4.9.122-g54068d6 #26 [ 25.173495] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 25.182925] task: ffff8801b6d61800 task.stack: ffff8801d94a8000 [ 25.188958] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 25.197820] RSP: 0018:ffff8801d94afca0 EFLAGS: 00010246 [ 25.203273] RAX: dffffc0000000000 RBX: ffff8801b6fa5180 RCX: 0000000000000000 [ 25.210855] RDX: 1ffff1003957fb50 RSI: ffffffff836c39a1 RDI: ffff8801cabfda80 [ 25.218208] RBP: ffff8801d94afcc0 R08: ffff8801b6d620e8 R09: 0000000000000000 [ 25.225585] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801cabfd900 [ 25.232892] R13: ffff8801b6fa5188 R14: 0000000000000000 R15: ffffffff83019be0 [ 25.240145] FS: 00000000015e3880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 25.248350] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 25.254213] CR2: 0000000000000080 CR3: 00000001bb094000 CR4: 00000000001606f0 [ 25.261536] Stack: [ 25.263674] ffff8801b6e4e600 ffff8801b6fa5180 ffff8801b6e4e9d0 ffff8801b6e4e8d8 [ 25.271694] ffff8801d94afce8 ffffffff836cb2b2 ffff8801b6e4ea40 ffff8801b6e4e600 [ 25.279694] ffffffff836cb1e0 ffff8801d94afd20 ffffffff830270f5 ffff8801b6e4ea40 [ 25.287733] Call Trace: [ 25.290442] [] pppol2tp_session_destruct+0xd2/0x110 [ 25.297132] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 25.303437] [] __sk_destruct+0x55/0x590 [ 25.309042] [] ? sock_release+0x1c0/0x1c0 [ 25.314820] [] sk_destruct+0x63/0x80 [ 25.320161] [] __sk_free+0x4f/0x220 [ 25.325420] [] sk_free+0x2b/0x40 [ 25.330429] [] pppol2tp_release+0x239/0x2e0 [ 25.336483] [] sock_release+0x96/0x1c0 [ 25.342002] [] sock_close+0x16/0x20 [ 25.347355] [] __fput+0x263/0x700 [ 25.352439] [] ____fput+0x15/0x20 [ 25.357519] [] task_work_run+0x10c/0x180 [ 25.363341] [] exit_to_usermode_loop+0xfc/0x120 [ 25.369650] [] do_syscall_64+0x364/0x490 [ 25.375496] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 25.382426] 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 [ 25.409950] RIP [] l2tp_session_free+0x11c/0x200 [ 25.416575] RSP [ 25.420247] CR2: 0000000000000080 [ 25.426415] ---[ end trace 8d7ce80581ca71cc ]--- [ 25.431208] Kernel panic - not syncing: Fatal exception [ 25.436891] Dumping ftrace buffer: [ 25.440412] (ftrace buffer empty) [ 25.444100] Kernel Offset: disabled [ 25.447705] Rebooting in 86400 seconds..