[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 14.650295] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 21.023337] random: sshd: uninitialized urandom read (32 bytes read) [ 21.640663] random: sshd: uninitialized urandom read (32 bytes read) [ 22.169626] random: sshd: uninitialized urandom read (32 bytes read) [ 22.308695] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.32' (ECDSA) to the list of known hosts. [ 27.892456] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 28.111352] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 28.119712] IP: [] l2tp_session_free+0x11c/0x200 [ 28.126315] PGD 1c1f6c067 [ 28.128961] PUD 1c1fe4067 PMD 0 [ 28.132454] [ 28.134079] Oops: 0002 [#1] PREEMPT SMP KASAN [ 28.138610] Dumping ftrace buffer: [ 28.142129] (ftrace buffer empty) [ 28.145817] Modules linked in: [ 28.149105] CPU: 1 PID: 3801 Comm: syz-executor722 Not tainted 4.9.123-g8dd3fc2 #79 [ 28.156931] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 28.166343] task: ffff8801b7eab000 task.stack: ffff8801b6430000 [ 28.172513] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 28.181374] RSP: 0018:ffff8801b6437ca0 EFLAGS: 00010246 [ 28.186797] RAX: dffffc0000000000 RBX: ffff8801b836ef00 RCX: 0000000000000000 [ 28.194044] RDX: 1ffff10036fbd610 RSI: ffffffff836c4991 RDI: ffff8801b7deb080 [ 28.201324] RBP: ffff8801b6437cc0 R08: ffff8801b7eab8e8 R09: 0000000000000000 [ 28.208587] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b7deaf00 [ 28.215837] R13: ffff8801b836ef08 R14: 0000000000000000 R15: ffffffff8301abe0 [ 28.223207] FS: 0000000001c7c880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 28.231412] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 28.237273] CR2: 0000000000000080 CR3: 00000001c2eee000 CR4: 00000000001606f0 [ 28.244523] Stack: [ 28.246660] ffff8801ba0cc400 ffff8801b836ef00 ffff8801ba0cc7d0 ffff8801ba0cc6d8 [ 28.254751] ffff8801b6437ce8 ffffffff836cc2a2 ffff8801ba0cc840 ffff8801ba0cc400 [ 28.262766] ffffffff836cc1d0 ffff8801b6437d20 ffffffff830280f5 ffff8801ba0cc840 [ 28.270930] Call Trace: [ 28.273565] [] pppol2tp_session_destruct+0xd2/0x110 [ 28.280251] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 28.286549] [] __sk_destruct+0x55/0x590 [ 28.292161] [] ? sock_release+0x1c0/0x1c0 [ 28.297949] [] sk_destruct+0x63/0x80 [ 28.303293] [] __sk_free+0x4f/0x220 [ 28.308552] [] sk_free+0x2b/0x40 [ 28.313649] [] pppol2tp_release+0x239/0x2e0 [ 28.319612] [] sock_release+0x96/0x1c0 [ 28.325132] [] sock_close+0x16/0x20 [ 28.330391] [] __fput+0x263/0x700 [ 28.335475] [] ____fput+0x15/0x20 [ 28.340558] [] task_work_run+0x10c/0x180 [ 28.346253] [] exit_to_usermode_loop+0xfc/0x120 [ 28.352559] [] do_syscall_64+0x364/0x490 [ 28.358355] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 28.365273] 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 c3 c9 fd 4c 89 ea 48 b8 00 [ 28.392708] RIP [] l2tp_session_free+0x11c/0x200 [ 28.399213] RSP [ 28.402828] CR2: 0000000000000080 [ 28.406344] ---[ end trace e9a2c488682999f1 ]--- [ 28.411095] Kernel panic - not syncing: Fatal exception [ 28.416763] Dumping ftrace buffer: [ 28.420282] (ftrace buffer empty) [ 28.423967] Kernel Offset: disabled [ 28.427572] Rebooting in 86400 seconds..