[....] Starting periodic command scheduler: cron[?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.283330] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c. [ 13.766889] random: sshd: uninitialized urandom read (32 bytes read) [ 13.921267] random: sshd: uninitialized urandom read (32 bytes read) Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 14.730150] random: sshd: uninitialized urandom read (32 bytes read) [ 14.886890] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.1' (ECDSA) to the list of known hosts. [ 20.311656] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 20.514160] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 20.522403] IP: [<ffffffff836bf9cc>] l2tp_session_free+0x11c/0x200 [ 20.528843] PGD 1ca68f067 [ 20.531486] PUD 1c8102067 PMD 0 [ 20.534956] [ 20.536571] Oops: 0002 [#1] PREEMPT SMP KASAN [ 20.541064] Dumping ftrace buffer: [ 20.544576] (ftrace buffer empty) [ 20.548269] Modules linked in: [ 20.551564] CPU: 1 PID: 3788 Comm: syz-executor504 Not tainted 4.9.119-g9dc978d #23 [ 20.559327] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 20.568684] task: ffff8801b8368000 task.stack: ffff8801b5e68000 [ 20.574727] RIP: 0010:[<ffffffff836bf9cc>] [<ffffffff836bf9cc>] l2tp_session_free+0x11c/0x200 [ 20.583583] RSP: 0018:ffff8801b5e6fca0 EFLAGS: 00010246 [ 20.589032] RAX: dffffc0000000000 RBX: ffff8801b77bcf00 RCX: 0000000000000000 [ 20.596280] RDX: 1ffff10036b9b5c0 RSI: ffffffff836bf9a1 RDI: ffff8801b5cdae00 [ 20.603657] RBP: ffff8801b5e6fcc0 R08: ffff8801b83688e8 R09: 0000000000000000 [ 20.610916] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b5cdac80 [ 20.618160] R13: ffff8801b77bcf08 R14: 0000000000000000 R15: ffffffff83015be0 [ 20.625402] FS: 0000000001055880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 20.633603] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 20.639472] CR2: 0000000000000080 CR3: 00000001ca694000 CR4: 00000000001606f0 [ 20.646717] Stack: [ 20.648851] ffff8801b5e40880 ffff8801b77bcf00 ffff8801b5e40c50 ffff8801b5e40b58 [ 20.657098] ffff8801b5e6fce8 ffffffff836c72b2 ffff8801b5e40cc0 ffff8801b5e40880 [ 20.665079] ffffffff836c71e0 ffff8801b5e6fd20 ffffffff830230f5 ffff8801b5e40cc0 [ 20.673076] Call Trace: [ 20.675653] [<ffffffff836c72b2>] pppol2tp_session_destruct+0xd2/0x110 [ 20.682811] [<ffffffff836c71e0>] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 20.689131] [<ffffffff830230f5>] __sk_destruct+0x55/0x590 [ 20.694732] [<ffffffff83015be0>] ? sock_release+0x1c0/0x1c0 [ 20.700504] [<ffffffff8302ab83>] sk_destruct+0x63/0x80 [ 20.705843] [<ffffffff8302abef>] __sk_free+0x4f/0x220 [ 20.711104] [<ffffffff8302adeb>] sk_free+0x2b/0x40 [ 20.716755] [<ffffffff836ca5b9>] pppol2tp_release+0x239/0x2e0 [ 20.722852] [<ffffffff83015ab6>] sock_release+0x96/0x1c0 [ 20.728365] [<ffffffff83015bf6>] sock_close+0x16/0x20 [ 20.733620] [<ffffffff81578693>] __fput+0x263/0x700 [ 20.738710] [<ffffffff81578bb5>] ____fput+0x15/0x20 [ 20.743790] [<ffffffff8119838c>] task_work_run+0x10c/0x180 [ 20.749477] [<ffffffff8100559c>] exit_to_usermode_loop+0xfc/0x120 [ 20.755768] [<ffffffff810064d4>] do_syscall_64+0x364/0x490 [ 20.761466] [<ffffffff839fccd3>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 20.768367] 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 f5 f0 c9 fd 4c 89 ea 48 b8 00 [ 20.795206] RIP [<ffffffff836bf9cc>] l2tp_session_free+0x11c/0x200 [ 20.801715] RSP <ffff8801b5e6fca0> [ 20.805307] CR2: 0000000000000080 [ 20.809024] ---[ end trace 64782a4e4e76299d ]--- [ 20.813768] Kernel panic - not syncing: Fatal exception [ 20.819404] Dumping ftrace buffer: [ 20.822929] (ftrace buffer empty) [ 20.826614] Kernel Offset: disabled [ 20.830214] Rebooting in 86400 seconds..