[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 12.375992] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 28.775715] random: sshd: uninitialized urandom read (32 bytes read) [ 29.081226] random: sshd: uninitialized urandom read (32 bytes read) [ 29.458263] random: sshd: uninitialized urandom read (32 bytes read) [ 40.259027] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.21' (ECDSA) to the list of known hosts. [ 45.735020] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 45.954531] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 45.962783] IP: [] l2tp_session_free+0x11c/0x200 [ 45.969214] PGD 1d950d067 [ 45.971874] PUD 1d950b067 PMD 0 [ 45.975348] [ 45.976989] Oops: 0002 [#1] PREEMPT SMP KASAN [ 45.981454] Dumping ftrace buffer: [ 45.984967] (ftrace buffer empty) [ 45.988647] Modules linked in: [ 45.991942] CPU: 0 PID: 3815 Comm: syz-executor791 Not tainted 4.9.117-g8b21e85 #19 [ 45.999710] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 46.009046] task: ffff8801b5e0b000 task.stack: ffff8801b5f90000 [ 46.015076] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 46.023926] RSP: 0018:ffff8801b5f97ca0 EFLAGS: 00010246 [ 46.029345] RAX: dffffc0000000000 RBX: ffff8801b6438280 RCX: 0000000000000000 [ 46.036589] RDX: 1ffff100395eb120 RSI: ffffffff836bf8f1 RDI: ffff8801caf58900 [ 46.043833] RBP: ffff8801b5f97cc0 R08: ffff8801b5e0b8e8 R09: 0000000000000000 [ 46.051093] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801caf58780 [ 46.058347] R13: ffff8801b6438288 R14: 0000000000000000 R15: ffffffff83015be0 [ 46.065593] FS: 0000000000b32880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 46.073790] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 46.079645] CR2: 0000000000000080 CR3: 00000001d9bab000 CR4: 00000000001606f0 [ 46.086887] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 46.094129] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 46.101370] Stack: [ 46.103492] ffff8801b774dd80 ffff8801b6438280 ffff8801b774e150 ffff8801b774e058 [ 46.111475] ffff8801b5f97ce8 ffffffff836c7202 ffff8801b774e1c0 ffff8801b774dd80 [ 46.119467] ffffffff836c7130 ffff8801b5f97d20 ffffffff83023095 ffff8801b774e1c0 [ 46.127447] Call Trace: [ 46.130012] [] pppol2tp_session_destruct+0xd2/0x110 [ 46.136648] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 46.142941] [] __sk_destruct+0x55/0x590 [ 46.148540] [] ? sock_release+0x1c0/0x1c0 [ 46.154308] [] sk_destruct+0x63/0x80 [ 46.159642] [] __sk_free+0x4f/0x220 [ 46.164887] [] sk_free+0x2b/0x40 [ 46.169874] [] pppol2tp_release+0x239/0x2e0 [ 46.175814] [] sock_release+0x96/0x1c0 [ 46.181332] [] sock_close+0x16/0x20 [ 46.186583] [] __fput+0x263/0x700 [ 46.191655] [] ____fput+0x15/0x20 [ 46.196742] [] task_work_run+0x10c/0x180 [ 46.202424] [] exit_to_usermode_loop+0xfc/0x120 [ 46.208712] [] do_syscall_64+0x364/0x490 [ 46.214408] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 46.221315] 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 e5 f1 c9 fd 4c 89 ea 48 b8 00 [ 46.248126] RIP [] l2tp_session_free+0x11c/0x200 [ 46.254632] RSP [ 46.258240] CR2: 0000000000000080 [ 46.261988] ---[ end trace 39671601a89f4f18 ]--- [ 46.266737] Kernel panic - not syncing: Fatal exception [ 46.272426] Dumping ftrace buffer: [ 46.275953] (ftrace buffer empty) [ 46.279635] Kernel Offset: disabled [ 46.283233] Rebooting in 86400 seconds..