[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 12.684645] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 16.809710] random: sshd: uninitialized urandom read (32 bytes read) [ 17.105505] random: sshd: uninitialized urandom read (32 bytes read) [ 18.074275] random: sshd: uninitialized urandom read (32 bytes read) [ 30.406485] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.29' (ECDSA) to the list of known hosts. [ 35.869007] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 36.092046] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 36.100280] IP: [] l2tp_session_free+0x11c/0x200 [ 36.106698] PGD 1bf353067 [ 36.109337] PUD 1bf32a067 PMD 0 [ 36.112811] [ 36.114430] Oops: 0002 [#1] PREEMPT SMP KASAN [ 36.118901] Dumping ftrace buffer: [ 36.122431] (ftrace buffer empty) [ 36.126124] Modules linked in: [ 36.129427] CPU: 0 PID: 3812 Comm: syz-executor189 Not tainted 4.9.113-g8956c50 #67 [ 36.137206] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 36.146546] task: ffff8801b86d6000 task.stack: ffff8801b6fa0000 [ 36.152663] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 36.161511] RSP: 0018:ffff8801b6fa7ca0 EFLAGS: 00010246 [ 36.166929] RAX: dffffc0000000000 RBX: ffff8801b5e16f00 RCX: 0000000000000000 [ 36.174173] RDX: 1ffff100390138d0 RSI: ffffffff836bcee1 RDI: ffff8801c809c680 [ 36.181416] RBP: ffff8801b6fa7cc0 R08: ffff8801b86d68e8 R09: 0000000000000000 [ 36.188661] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801c809c500 [ 36.195902] R13: ffff8801b5e16f08 R14: 0000000000000000 R15: ffffffff83013be0 [ 36.203154] FS: 0000000001f3a880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 36.211350] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 36.217203] CR2: 0000000000000080 CR3: 00000001c713f000 CR4: 00000000001606f0 [ 36.224619] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 36.231869] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 36.239108] Stack: [ 36.241228] ffff8801b6c26600 ffff8801b5e16f00 ffff8801b6c269d0 ffff8801b6c268d8 [ 36.249218] ffff8801b6fa7ce8 ffffffff836c47f2 ffff8801b6c26a40 ffff8801b6c26600 [ 36.257208] ffffffff836c4720 ffff8801b6fa7d20 ffffffff83021095 ffff8801b6c26a40 [ 36.265182] Call Trace: [ 36.267748] [] pppol2tp_session_destruct+0xd2/0x110 [ 36.274392] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 36.280768] [] __sk_destruct+0x55/0x590 [ 36.286371] [] ? sock_release+0x1c0/0x1c0 [ 36.292138] [] sk_destruct+0x63/0x80 [ 36.297558] [] __sk_free+0x4f/0x220 [ 36.302802] [] sk_free+0x2b/0x40 [ 36.307787] [] pppol2tp_release+0x239/0x2e0 [ 36.313730] [] sock_release+0x96/0x1c0 [ 36.319235] [] sock_close+0x16/0x20 [ 36.324504] [] __fput+0x263/0x700 [ 36.329576] [] ____fput+0x15/0x20 [ 36.334747] [] task_work_run+0x10c/0x180 [ 36.340439] [] exit_to_usermode_loop+0xfc/0x120 [ 36.346727] [] do_syscall_64+0x364/0x490 [ 36.352411] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 36.359301] 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 1b ca fd 4c 89 ea 48 b8 00 [ 36.386232] RIP [] l2tp_session_free+0x11c/0x200 [ 36.392725] RSP [ 36.396319] CR2: 0000000000000080 [ 36.399962] ---[ end trace 9cc8ff2338118c55 ]--- [ 36.404705] Kernel panic - not syncing: Fatal exception [ 36.410442] Dumping ftrace buffer: [ 36.413958] (ftrace buffer empty) [ 36.417640] Kernel Offset: disabled [ 36.421248] Rebooting in 86400 seconds..