[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.566811] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. [ 14.342825] random: sshd: uninitialized urandom read (32 bytes read) [ 14.634608] random: sshd: uninitialized urandom read (32 bytes read) Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 15.121578] random: sshd: uninitialized urandom read (32 bytes read) [ 15.256228] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.53' (ECDSA) to the list of known hosts. [ 20.951891] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 21.157282] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 21.165504] IP: [] l2tp_session_free+0x11c/0x200 [ 21.171955] PGD 1c16b4067 [ 21.174603] PUD 1c17e9067 PMD 0 [ 21.178093] [ 21.179719] Oops: 0002 [#1] PREEMPT SMP KASAN [ 21.184193] Dumping ftrace buffer: [ 21.187727] (ftrace buffer empty) [ 21.191414] Modules linked in: [ 21.194710] CPU: 0 PID: 3794 Comm: syz-executor517 Not tainted 4.9.117-g8b21e85 #19 [ 21.202477] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 21.211809] task: ffff8801b83ec800 task.stack: ffff8801b66b0000 [ 21.217847] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 21.226726] RSP: 0018:ffff8801b66b7ca0 EFLAGS: 00010246 [ 21.232157] RAX: dffffc0000000000 RBX: ffff8801b696e780 RCX: 0000000000000000 [ 21.239434] RDX: 1ffff10038fa6fa0 RSI: ffffffff836bf8f1 RDI: ffff8801c7d37d00 [ 21.246681] RBP: ffff8801b66b7cc0 R08: ffff8801b83ed0e8 R09: 0000000000000000 [ 21.253936] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801c7d37b80 [ 21.261214] R13: ffff8801b696e788 R14: 0000000000000000 R15: ffffffff83015be0 [ 21.268466] FS: 0000000002110880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 21.276683] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 21.282553] CR2: 0000000000000080 CR3: 00000001bf314000 CR4: 00000000001606f0 [ 21.289800] Stack: [ 21.291926] ffff8801ca43cc80 ffff8801b696e780 ffff8801ca43d050 ffff8801ca43cf58 [ 21.299930] ffff8801b66b7ce8 ffffffff836c7202 ffff8801ca43d0c0 ffff8801ca43cc80 [ 21.307942] ffffffff836c7130 ffff8801b66b7d20 ffffffff83023095 ffff8801ca43d0c0 [ 21.315957] Call Trace: [ 21.318524] [] pppol2tp_session_destruct+0xd2/0x110 [ 21.325182] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 21.331489] [] __sk_destruct+0x55/0x590 [ 21.337095] [] ? sock_release+0x1c0/0x1c0 [ 21.342868] [] sk_destruct+0x63/0x80 [ 21.348211] [] __sk_free+0x4f/0x220 [ 21.353466] [] sk_free+0x2b/0x40 [ 21.358462] [] pppol2tp_release+0x239/0x2e0 [ 21.364416] [] sock_release+0x96/0x1c0 [ 21.369939] [] sock_close+0x16/0x20 [ 21.375203] [] __fput+0x263/0x700 [ 21.380289] [] ____fput+0x15/0x20 [ 21.385372] [] task_work_run+0x10c/0x180 [ 21.391063] [] exit_to_usermode_loop+0xfc/0x120 [ 21.397364] [] do_syscall_64+0x364/0x490 [ 21.403056] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 21.409963] 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 [ 21.437282] RIP [] l2tp_session_free+0x11c/0x200 [ 21.443803] RSP [ 21.447406] CR2: 0000000000000080 [ 21.451252] ---[ end trace 83503a95ebeebad0 ]--- [ 21.456015] Kernel panic - not syncing: Fatal exception [ 21.461765] Dumping ftrace buffer: [ 21.465305] (ftrace buffer empty) [ 21.468993] Kernel Offset: disabled [ 21.472620] Rebooting in 86400 seconds..