[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 11.991239] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 14.610771] random: sshd: uninitialized urandom read (32 bytes read) [ 14.788659] random: sshd: uninitialized urandom read (32 bytes read) [ 15.760961] random: sshd: uninitialized urandom read (32 bytes read) [ 24.054631] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.24' (ECDSA) to the list of known hosts. [ 29.468652] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 29.674043] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 29.682308] IP: [] l2tp_session_free+0x11c/0x200 [ 29.688739] PGD 1c4dd6067 [ 29.691379] PUD 1c2a87067 PMD 0 [ 29.694857] [ 29.696474] Oops: 0002 [#1] PREEMPT SMP KASAN [ 29.700943] Dumping ftrace buffer: [ 29.704453] (ftrace buffer empty) [ 29.708134] Modules linked in: [ 29.711415] CPU: 1 PID: 3806 Comm: syz-executor426 Not tainted 4.9.113-g47bbcd6 #10 [ 29.719178] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 29.728503] task: ffff8801b736c800 task.stack: ffff8801b5818000 [ 29.734529] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 29.743374] RSP: 0018:ffff8801b581fca0 EFLAGS: 00010246 [ 29.748793] RAX: dffffc0000000000 RBX: ffff8801cb70e500 RCX: 0000000000000000 [ 29.756036] RDX: 1ffff10036e0ac30 RSI: ffffffff836bcce1 RDI: ffff8801b7056180 [ 29.763284] RBP: ffff8801b581fcc0 R08: ffff8801b736d0e8 R09: 0000000000000000 [ 29.770528] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b7056000 [ 29.777797] R13: ffff8801cb70e508 R14: 0000000000000000 R15: ffffffff83013be0 [ 29.785040] FS: 000000000161d880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 29.793242] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 29.799109] CR2: 0000000000000080 CR3: 00000001be5ea000 CR4: 00000000001606f0 [ 29.806358] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 29.813605] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 29.820845] Stack: [ 29.822969] ffff8801d96b9980 ffff8801cb70e500 ffff8801d96b9d50 ffff8801d96b9c58 [ 29.830970] ffff8801b581fce8 ffffffff836c45f2 ffff8801d96b9dc0 ffff8801d96b9980 [ 29.838959] ffffffff836c4520 ffff8801b581fd20 ffffffff83021095 ffff8801d96b9dc0 [ 29.846944] Call Trace: [ 29.849510] [] pppol2tp_session_destruct+0xd2/0x110 [ 29.856159] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 29.862457] [] __sk_destruct+0x55/0x590 [ 29.868070] [] ? sock_release+0x1c0/0x1c0 [ 29.873844] [] sk_destruct+0x63/0x80 [ 29.879180] [] __sk_free+0x4f/0x220 [ 29.884428] [] sk_free+0x2b/0x40 [ 29.889430] [] pppol2tp_release+0x239/0x2e0 [ 29.895374] [] sock_release+0x96/0x1c0 [ 29.900884] [] sock_close+0x16/0x20 [ 29.906133] [] __fput+0x263/0x700 [ 29.911206] [] ____fput+0x15/0x20 [ 29.916298] [] task_work_run+0x10c/0x180 [ 29.921981] [] exit_to_usermode_loop+0xfc/0x120 [ 29.928272] [] do_syscall_64+0x364/0x490 [ 29.933956] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 29.940853] 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 55 1d ca fd 4c 89 ea 48 b8 00 [ 29.967601] RIP [] l2tp_session_free+0x11c/0x200 [ 29.974105] RSP [ 29.977701] CR2: 0000000000000080 [ 29.981334] ---[ end trace b1bd5f8c7d6b1abd ]--- [ 29.986079] Kernel panic - not syncing: Fatal exception [ 29.991792] Dumping ftrace buffer: [ 29.995307] (ftrace buffer empty) [ 29.999261] Kernel Offset: disabled [ 30.002863] Rebooting in 86400 seconds..