[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.971864] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. [ 14.161598] random: sshd: uninitialized urandom read (32 bytes read) [ 14.670409] random: sshd: uninitialized urandom read (32 bytes read) Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 15.194220] random: sshd: uninitialized urandom read (32 bytes read) [ 15.354525] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.15.204' (ECDSA) to the list of known hosts. [ 20.942281] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 21.150854] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 21.159309] IP: [] l2tp_session_free+0x11c/0x200 [ 21.165764] PGD 1ca7a7067 [ 21.168421] PUD 1c9d5f067 PMD 0 [ 21.171931] [ 21.173569] Oops: 0002 [#1] PREEMPT SMP KASAN [ 21.178057] Dumping ftrace buffer: [ 21.181601] (ftrace buffer empty) [ 21.185301] Modules linked in: [ 21.188617] CPU: 1 PID: 3798 Comm: syz-executor225 Not tainted 4.9.119-g9dc978d #75 [ 21.196397] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 21.205893] task: ffff8801b853b000 task.stack: ffff8801b64a8000 [ 21.211953] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 21.220856] RSP: 0018:ffff8801b64afca0 EFLAGS: 00010246 [ 21.226296] RAX: dffffc0000000000 RBX: ffff8801b64dac80 RCX: 0000000000000000 [ 21.233674] RDX: 1ffff100393b8880 RSI: ffffffff836bf9a1 RDI: ffff8801c9dc4400 [ 21.240940] RBP: ffff8801b64afcc0 R08: ffff8801b853b8e8 R09: 0000000000000000 [ 21.248210] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801c9dc4280 [ 21.255496] R13: ffff8801b64dac88 R14: 0000000000000000 R15: ffffffff83015be0 [ 21.262760] FS: 0000000000eee880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 21.270982] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 21.276875] CR2: 0000000000000080 CR3: 00000001ccac0000 CR4: 00000000001606f0 [ 21.284147] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 21.291716] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 21.298975] Stack: [ 21.301116] ffff8801b6b3e600 ffff8801b64dac80 ffff8801b6b3e9d0 ffff8801b6b3e8d8 [ 21.309357] ffff8801b64afce8 ffffffff836c72b2 ffff8801b6b3ea40 ffff8801b6b3e600 [ 21.317435] ffffffff836c71e0 ffff8801b64afd20 ffffffff830230f5 ffff8801b6b3ea40 [ 21.325490] Call Trace: [ 21.328073] [] pppol2tp_session_destruct+0xd2/0x110 [ 21.334735] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 21.341047] [] __sk_destruct+0x55/0x590 [ 21.346661] [] ? sock_release+0x1c0/0x1c0 [ 21.352449] [] sk_destruct+0x63/0x80 [ 21.357803] [] __sk_free+0x4f/0x220 [ 21.363302] [] sk_free+0x2b/0x40 [ 21.368316] [] pppol2tp_release+0x239/0x2e0 [ 21.374289] [] sock_release+0x96/0x1c0 [ 21.379948] [] sock_close+0x16/0x20 [ 21.385225] [] __fput+0x263/0x700 [ 21.390322] [] ____fput+0x15/0x20 [ 21.395567] [] task_work_run+0x10c/0x180 [ 21.401285] [] exit_to_usermode_loop+0xfc/0x120 [ 21.407596] [] do_syscall_64+0x364/0x490 [ 21.413302] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 21.420221] 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 [ 21.448621] RIP [] l2tp_session_free+0x11c/0x200 [ 21.455164] RSP [ 21.458790] CR2: 0000000000000080 [ 21.462339] ---[ end trace 4d6be96a2f60eb7d ]--- [ 21.468287] Kernel panic - not syncing: Fatal exception [ 21.474364] Dumping ftrace buffer: [ 21.477902] (ftrace buffer empty) [ 21.481614] Kernel Offset: disabled [ 21.485233] Rebooting in 86400 seconds..