[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 11.628121] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 21.510092] random: sshd: uninitialized urandom read (32 bytes read) [ 21.930842] random: sshd: uninitialized urandom read (32 bytes read) [ 22.540548] random: sshd: uninitialized urandom read (32 bytes read) [ 29.858398] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.50' (ECDSA) to the list of known hosts. [ 35.220103] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 35.425342] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 35.433594] IP: [] l2tp_session_free+0x11c/0x200 [ 35.440007] PGD 1ba4c6067 [ 35.442658] PUD 1bb767067 PMD 0 [ 35.446130] [ 35.447747] Oops: 0002 [#1] PREEMPT SMP KASAN [ 35.452211] Dumping ftrace buffer: [ 35.455718] (ftrace buffer empty) [ 35.459398] Modules linked in: [ 35.462689] CPU: 0 PID: 3797 Comm: syz-executor747 Not tainted 4.9.113-g47bbcd6 #62 [ 35.470453] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 35.479779] task: ffff8801b8cc1800 task.stack: ffff8801d8e18000 [ 35.485804] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 35.494643] RSP: 0018:ffff8801d8e1fca0 EFLAGS: 00010246 [ 35.500061] RAX: dffffc0000000000 RBX: ffff8801c923a500 RCX: 0000000000000000 [ 35.507320] RDX: 1ffff10036ca78d0 RSI: ffffffff836bcce1 RDI: ffff8801b653c680 [ 35.514560] RBP: ffff8801d8e1fcc0 R08: ffff8801b8cc20e8 R09: 0000000000000000 [ 35.521799] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b653c500 [ 35.529039] R13: ffff8801c923a508 R14: 0000000000000000 R15: ffffffff83013be0 [ 35.536284] FS: 000000000219a880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 35.544491] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 35.550343] CR2: 0000000000000080 CR3: 00000001ba4ba000 CR4: 00000000001606f0 [ 35.557586] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 35.564825] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 35.572065] Stack: [ 35.574188] ffff8801d9639980 ffff8801c923a500 ffff8801d9639d50 ffff8801d9639c58 [ 35.582173] ffff8801d8e1fce8 ffffffff836c45f2 ffff8801d9639dc0 ffff8801d9639980 [ 35.590158] ffffffff836c4520 ffff8801d8e1fd20 ffffffff83021095 ffff8801d9639dc0 [ 35.598173] Call Trace: [ 35.600736] [] pppol2tp_session_destruct+0xd2/0x110 [ 35.607369] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 35.613658] [] __sk_destruct+0x55/0x590 [ 35.619253] [] ? sock_release+0x1c0/0x1c0 [ 35.625020] [] sk_destruct+0x63/0x80 [ 35.630355] [] __sk_free+0x4f/0x220 [ 35.635599] [] sk_free+0x2b/0x40 [ 35.640584] [] pppol2tp_release+0x239/0x2e0 [ 35.646524] [] sock_release+0x96/0x1c0 [ 35.652029] [] sock_close+0x16/0x20 [ 35.657275] [] __fput+0x263/0x700 [ 35.662347] [] ____fput+0x15/0x20 [ 35.667424] [] task_work_run+0x10c/0x180 [ 35.673107] [] exit_to_usermode_loop+0xfc/0x120 [ 35.679395] [] do_syscall_64+0x364/0x490 [ 35.685076] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 35.691969] 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 [ 35.718772] RIP [] l2tp_session_free+0x11c/0x200 [ 35.725267] RSP [ 35.728863] CR2: 0000000000000080 [ 35.732642] ---[ end trace c4e9ee9de7691b18 ]--- [ 35.737394] Kernel panic - not syncing: Fatal exception [ 35.743131] Dumping ftrace buffer: [ 35.746641] (ftrace buffer empty) [ 35.750321] Kernel Offset: disabled [ 35.753933] Rebooting in 86400 seconds..