[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 13.238548] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 16.941894] random: sshd: uninitialized urandom read (32 bytes read) [ 17.272599] random: sshd: uninitialized urandom read (32 bytes read) [ 18.219647] random: sshd: uninitialized urandom read (32 bytes read) [ 18.357051] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.54' (ECDSA) to the list of known hosts. [ 23.762054] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 23.977853] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 23.986117] IP: [] l2tp_session_free+0x11c/0x200 [ 23.992534] PGD 1c6037067 [ 23.995176] PUD 1c637d067 PMD 0 [ 23.998654] [ 24.000277] Oops: 0002 [#1] PREEMPT SMP KASAN [ 24.004755] Dumping ftrace buffer: [ 24.008267] (ftrace buffer empty) [ 24.011949] Modules linked in: [ 24.015243] CPU: 0 PID: 3688 Comm: syz-executor239 Not tainted 4.9.113-g47bbcd6 #10 [ 24.023007] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 24.032344] task: ffff8801c1d71800 task.stack: ffff8801c16c0000 [ 24.038377] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 24.047221] RSP: 0018:ffff8801c16c7ca0 EFLAGS: 00010246 [ 24.052671] RAX: dffffc0000000000 RBX: ffff8801c2124c80 RCX: 0000000000000000 [ 24.059923] RDX: 1ffff10038424a60 RSI: ffffffff836bcce1 RDI: ffff8801c2125300 [ 24.067167] RBP: ffff8801c16c7cc0 R08: ffff8801c1d720e8 R09: 0000000000000000 [ 24.074417] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801c2125180 [ 24.081720] R13: ffff8801c2124c88 R14: 0000000000000000 R15: ffffffff83013be0 [ 24.088965] FS: 00000000013fb880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 24.097174] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 24.103029] CR2: 0000000000000080 CR3: 00000001c6915000 CR4: 00000000001606f0 [ 24.110275] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 24.117518] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 24.124767] Stack: [ 24.126888] ffff8801c257aa80 ffff8801c2124c80 ffff8801c257ae50 ffff8801c257ad58 [ 24.134893] ffff8801c16c7ce8 ffffffff836c45f2 ffff8801c257aec0 ffff8801c257aa80 [ 24.142906] ffffffff836c4520 ffff8801c16c7d20 ffffffff83021095 ffff8801c257aec0 [ 24.150892] Call Trace: [ 24.153456] [] pppol2tp_session_destruct+0xd2/0x110 [ 24.160102] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 24.166397] [] __sk_destruct+0x55/0x590 [ 24.171999] [] ? sock_release+0x1c0/0x1c0 [ 24.177772] [] sk_destruct+0x63/0x80 [ 24.183115] [] __sk_free+0x4f/0x220 [ 24.188371] [] sk_free+0x2b/0x40 [ 24.193362] [] pppol2tp_release+0x239/0x2e0 [ 24.199318] [] sock_release+0x96/0x1c0 [ 24.204837] [] sock_close+0x16/0x20 [ 24.210100] [] __fput+0x263/0x700 [ 24.215185] [] ____fput+0x15/0x20 [ 24.220273] [] task_work_run+0x10c/0x180 [ 24.225959] [] exit_to_usermode_loop+0xfc/0x120 [ 24.232249] [] do_syscall_64+0x364/0x490 [ 24.237934] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 24.244838] 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 [ 24.271734] RIP [] l2tp_session_free+0x11c/0x200 [ 24.278248] RSP [ 24.281846] CR2: 0000000000000080 [ 24.285448] ---[ end trace 9c6d33d05751f600 ]--- [ 24.290219] Kernel panic - not syncing: Fatal exception [ 24.295924] Dumping ftrace buffer: [ 24.299442] (ftrace buffer empty) [ 24.303129] Kernel Offset: disabled [ 24.306741] Rebooting in 86400 seconds..