[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 12.505446] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 21.356152] random: sshd: uninitialized urandom read (32 bytes read) [ 21.728504] random: sshd: uninitialized urandom read (32 bytes read) [ 22.101867] random: sshd: uninitialized urandom read (32 bytes read) [ 39.650788] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.40' (ECDSA) to the list of known hosts. [ 45.076051] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 45.276731] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 45.284946] IP: [] l2tp_session_free+0x11c/0x200 [ 45.291377] PGD 1c6aae067 [ 45.294019] PUD 1c689b067 PMD 0 [ 45.297504] [ 45.299124] Oops: 0002 [#1] PREEMPT SMP KASAN [ 45.303591] Dumping ftrace buffer: [ 45.307101] (ftrace buffer empty) [ 45.310785] Modules linked in: [ 45.314117] CPU: 0 PID: 3697 Comm: syz-executor285 Not tainted 4.9.117-g8b21e85 #19 [ 45.321885] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 45.331217] task: ffff8801c336b000 task.stack: ffff8801c23e8000 [ 45.337251] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 45.346108] RSP: 0018:ffff8801c23efca0 EFLAGS: 00010246 [ 45.351532] RAX: dffffc0000000000 RBX: ffff8801c2f2f680 RCX: 0000000000000000 [ 45.358779] RDX: 1ffff10038544d70 RSI: ffffffff836bf8f1 RDI: ffff8801c2a26b80 [ 45.366027] RBP: ffff8801c23efcc0 R08: ffff8801c336b8e8 R09: 0000000000000000 [ 45.373274] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801c2a26a00 [ 45.380519] R13: ffff8801c2f2f688 R14: 0000000000000000 R15: ffffffff83015be0 [ 45.387767] FS: 0000000000f56880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 45.395981] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 45.401839] CR2: 0000000000000080 CR3: 00000001c83aa000 CR4: 00000000001606f0 [ 45.409088] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 45.416335] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 45.423578] Stack: [ 45.425704] ffff8801c3f58000 ffff8801c2f2f680 ffff8801c3f583d0 ffff8801c3f582d8 [ 45.433704] ffff8801c23efce8 ffffffff836c7202 ffff8801c3f58440 ffff8801c3f58000 [ 45.441692] ffffffff836c7130 ffff8801c23efd20 ffffffff83023095 ffff8801c3f58440 [ 45.449684] Call Trace: [ 45.452245] [] pppol2tp_session_destruct+0xd2/0x110 [ 45.458896] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 45.465191] [] __sk_destruct+0x55/0x590 [ 45.470791] [] ? sock_release+0x1c0/0x1c0 [ 45.476566] [] sk_destruct+0x63/0x80 [ 45.481907] [] __sk_free+0x4f/0x220 [ 45.487171] [] sk_free+0x2b/0x40 [ 45.492164] [] pppol2tp_release+0x239/0x2e0 [ 45.498113] [] sock_release+0x96/0x1c0 [ 45.503627] [] sock_close+0x16/0x20 [ 45.508881] [] __fput+0x263/0x700 [ 45.513961] [] ____fput+0x15/0x20 [ 45.519042] [] task_work_run+0x10c/0x180 [ 45.524733] [] exit_to_usermode_loop+0xfc/0x120 [ 45.531033] [] do_syscall_64+0x364/0x490 [ 45.536732] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 45.543648] 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 e5 f1 c9 fd 4c 89 ea 48 b8 00 [ 45.570395] RIP [] l2tp_session_free+0x11c/0x200 [ 45.576896] RSP [ 45.580498] CR2: 0000000000000080 [ 45.584154] ---[ end trace 7ffdaba32ce9386d ]--- [ 45.588913] Kernel panic - not syncing: Fatal exception [ 45.594526] Dumping ftrace buffer: [ 45.598043] (ftrace buffer empty) [ 45.601729] Kernel Offset: disabled [ 45.605347] Rebooting in 86400 seconds..