[....] Starting periodic command scheduler: cron[?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 12.009872] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 14.532084] random: sshd: uninitialized urandom read (32 bytes read) [ 14.682781] random: sshd: uninitialized urandom read (32 bytes read) [ 15.259727] random: sshd: uninitialized urandom read (32 bytes read) [ 29.688565] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.26' (ECDSA) to the list of known hosts. [ 35.276282] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 35.472703] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 35.480930] IP: [<ffffffff836c473c>] l2tp_session_free+0x11c/0x200 [ 35.487367] PGD 1c3c5c067 [ 35.490010] PUD 1c4934067 PMD 0 [ 35.493486] [ 35.495108] Oops: 0002 [#1] PREEMPT SMP KASAN [ 35.499697] Dumping ftrace buffer: [ 35.503215] (ftrace buffer empty) [ 35.506909] Modules linked in: [ 35.510340] CPU: 0 PID: 3735 Comm: syz-executor699 Not tainted 4.9.124-g09eb2ba #83 [ 35.518146] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 35.527482] task: ffff8801c1784800 task.stack: ffff8801be490000 [ 35.533569] RIP: 0010:[<ffffffff836c473c>] [<ffffffff836c473c>] l2tp_session_free+0x11c/0x200 [ 35.542437] RSP: 0018:ffff8801be497c98 EFLAGS: 00010246 [ 35.547864] RAX: dffffc0000000000 RBX: ffff8801cb763680 RCX: 0000000000000000 [ 35.555111] RDX: 1ffff10037d648d0 RSI: ffffffff836c4711 RDI: ffff8801beb24680 [ 35.562356] RBP: ffff8801be497cb8 R08: ffff8801c17850e8 R09: 0000000000000000 [ 35.569607] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801beb24500 [ 35.576853] R13: ffff8801cb763688 R14: 0000000000000000 R15: 0000000000000000 [ 35.584269] FS: 00000000017d3880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 35.592474] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 35.598334] CR2: 0000000000000080 CR3: 00000001c48d6000 CR4: 00000000001606f0 [ 35.605812] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 35.613065] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 35.620311] Stack: [ 35.622436] ffff8801bf2ccc80 ffff8801cb763680 ffff8801bf2cd050 ffff8801bf2ccf58 [ 35.630422] ffff8801be497ce0 ffffffff836cc022 ffff8801bf2cd0c0 ffff8801bf2ccc80 [ 35.638448] ffffffff836cbf50 ffff8801be497d18 ffffffff830281f5 ffff8801bf2cd0c0 [ 35.646447] Call Trace: [ 35.649014] [<ffffffff836cc022>] pppol2tp_session_destruct+0xd2/0x110 [ 35.655662] [<ffffffff836cbf50>] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 35.661959] [<ffffffff830281f5>] __sk_destruct+0x55/0x590 [ 35.667630] [<ffffffff8302fc83>] sk_destruct+0x63/0x80 [ 35.672977] [<ffffffff8302fcef>] __sk_free+0x4f/0x220 [ 35.678230] [<ffffffff8302feeb>] sk_free+0x2b/0x40 [ 35.683228] [<ffffffff836cf329>] pppol2tp_release+0x239/0x2e0 [ 35.689176] [<ffffffff83018357>] __sock_release+0xd7/0x260 [ 35.695004] [<ffffffff830184e0>] ? __sock_release+0x260/0x260 [ 35.700956] [<ffffffff830184f9>] sock_close+0x19/0x20 [ 35.706212] [<ffffffff8157ca73>] __fput+0x263/0x700 [ 35.711291] [<ffffffff8157cf95>] ____fput+0x15/0x20 [ 35.716370] [<ffffffff8119a66c>] task_work_run+0x10c/0x180 [ 35.722060] [<ffffffff8100559c>] exit_to_usermode_loop+0xfc/0x120 [ 35.728355] [<ffffffff810064d4>] do_syscall_64+0x364/0x490 [ 35.734045] [<ffffffff83a019d3>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 35.740994] 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 <f0> 41 ff 8e 80 00 00 00 74 69 e8 a5 c5 c9 fd 4c 89 ea 48 b8 00 [ 35.768339] RIP [<ffffffff836c473c>] l2tp_session_free+0x11c/0x200 [ 35.774904] RSP <ffff8801be497c98> [ 35.778516] CR2: 0000000000000080 [ 35.782022] ---[ end trace d8b835a7c77a3077 ]--- [ 35.786785] Kernel panic - not syncing: Fatal exception [ 35.792470] Dumping ftrace buffer: [ 35.795989] (ftrace buffer empty) [ 35.799677] Kernel Offset: disabled [ 35.803276] Rebooting in 86400 seconds..