[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 12.666872] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 16.269996] random: sshd: uninitialized urandom read (32 bytes read) [ 16.533062] random: sshd: uninitialized urandom read (32 bytes read) [ 17.061527] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.15.206' (ECDSA) to the list of known hosts. [ 22.661783] urandom_read: 1 callbacks suppressed [ 22.661787] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 22.875796] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 22.884077] IP: [] l2tp_session_free+0x11c/0x200 [ 22.890645] PGD 1c1460067 [ 22.893299] PUD 1c143b067 PMD 0 [ 22.896771] [ 22.898388] Oops: 0002 [#1] PREEMPT SMP KASAN [ 22.902865] Dumping ftrace buffer: [ 22.906381] (ftrace buffer empty) [ 22.910063] Modules linked in: [ 22.913380] CPU: 1 PID: 3788 Comm: syz-executor855 Not tainted 4.9.117-g8b21e85 #71 [ 22.921174] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 22.930504] task: ffff8801b9161800 task.stack: ffff8801b9358000 [ 22.936548] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 22.945470] RSP: 0018:ffff8801b935fca0 EFLAGS: 00010246 [ 22.950890] RAX: dffffc0000000000 RBX: ffff8801b93ef680 RCX: 0000000000000000 [ 22.958130] RDX: 1ffff10037245d20 RSI: ffffffff836bf8f1 RDI: ffff8801b922e900 [ 22.965386] RBP: ffff8801b935fcc0 R08: ffff8801b91620e8 R09: 0000000000000000 [ 22.972630] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b922e780 [ 22.979878] R13: ffff8801b93ef688 R14: 0000000000000000 R15: ffffffff83015be0 [ 22.987139] FS: 0000000001cfb880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 22.995338] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 23.001191] CR2: 0000000000000080 CR3: 00000001c2657000 CR4: 00000000001606f0 [ 23.008436] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 23.015680] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 23.022921] Stack: [ 23.025088] ffff8801c63c6e80 ffff8801b93ef680 ffff8801c63c7250 ffff8801c63c7158 [ 23.033067] ffff8801b935fce8 ffffffff836c7202 ffff8801c63c72c0 ffff8801c63c6e80 [ 23.041169] ffffffff836c7130 ffff8801b935fd20 ffffffff83023095 ffff8801c63c72c0 [ 23.049144] Call Trace: [ 23.051713] [] pppol2tp_session_destruct+0xd2/0x110 [ 23.058371] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 23.064675] [] __sk_destruct+0x55/0x590 [ 23.070276] [] ? sock_release+0x1c0/0x1c0 [ 23.076057] [] sk_destruct+0x63/0x80 [ 23.081396] [] __sk_free+0x4f/0x220 [ 23.086669] [] sk_free+0x2b/0x40 [ 23.091661] [] pppol2tp_release+0x239/0x2e0 [ 23.097624] [] sock_release+0x96/0x1c0 [ 23.103132] [] sock_close+0x16/0x20 [ 23.108378] [] __fput+0x263/0x700 [ 23.113487] [] ____fput+0x15/0x20 [ 23.118594] [] task_work_run+0x10c/0x180 [ 23.124281] [] exit_to_usermode_loop+0xfc/0x120 [ 23.130579] [] do_syscall_64+0x364/0x490 [ 23.136271] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 23.143176] 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 [ 23.170422] RIP [] l2tp_session_free+0x11c/0x200 [ 23.176956] RSP [ 23.180565] CR2: 0000000000000080 [ 23.184155] ---[ end trace 2ae10294e3477bf8 ]--- [ 23.188901] Kernel panic - not syncing: Fatal exception [ 23.194547] Dumping ftrace buffer: [ 23.198071] (ftrace buffer empty) [ 23.201755] Kernel Offset: disabled [ 23.205354] Rebooting in 86400 seconds..