[....] 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[ 13.158041] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 16.158386] random: sshd: uninitialized urandom read (32 bytes read) [ 16.422163] random: sshd: uninitialized urandom read (32 bytes read) [ 16.957226] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.19' (ECDSA) to the list of known hosts. [ 22.844060] urandom_read: 1 callbacks suppressed [ 22.844063] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 23.051540] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 23.059783] IP: [] l2tp_session_free+0x11c/0x200 [ 23.066230] PGD 1c6a80067 [ 23.068879] PUD 1c6a78067 PMD 0 [ 23.072382] [ 23.074048] Oops: 0002 [#1] PREEMPT SMP KASAN [ 23.078531] Dumping ftrace buffer: [ 23.082053] (ftrace buffer empty) [ 23.085748] Modules linked in: [ 23.089066] CPU: 0 PID: 3665 Comm: syz-executor415 Not tainted 4.9.121-g681e57b #77 [ 23.096850] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 23.106465] task: ffff8801c43e6000 task.stack: ffff8801c2cb0000 [ 23.112507] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 23.121382] RSP: 0018:ffff8801c2cb7ca0 EFLAGS: 00010246 [ 23.126822] RAX: dffffc0000000000 RBX: ffff8801c2d60a00 RCX: 0000000000000000 [ 23.134079] RDX: 1ffff100385a3c80 RSI: ffffffff836c29a1 RDI: ffff8801c2d1e400 [ 23.141456] RBP: ffff8801c2cb7cc0 R08: ffff8801c43e68e8 R09: 0000000000000000 [ 23.148719] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801c2d1e280 [ 23.155974] R13: ffff8801c2d60a08 R14: 0000000000000000 R15: ffffffff83018be0 [ 23.163228] FS: 0000000001137880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 23.171456] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 23.177327] CR2: 0000000000000080 CR3: 00000001cb7c7000 CR4: 00000000001606f0 [ 23.184582] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 23.191836] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 23.199088] Stack: [ 23.201222] ffff8801c365b300 ffff8801c2d60a00 ffff8801c365b6d0 ffff8801c365b5d8 [ 23.209316] ffff8801c2cb7ce8 ffffffff836ca2b2 ffff8801c365b740 ffff8801c365b300 [ 23.217376] ffffffff836ca1e0 ffff8801c2cb7d20 ffffffff830260f5 ffff8801c365b740 [ 23.225407] Call Trace: [ 23.227981] [] pppol2tp_session_destruct+0xd2/0x110 [ 23.234633] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 23.240936] [] __sk_destruct+0x55/0x590 [ 23.246549] [] ? sock_release+0x1c0/0x1c0 [ 23.252329] [] sk_destruct+0x63/0x80 [ 23.257674] [] __sk_free+0x4f/0x220 [ 23.262936] [] sk_free+0x2b/0x40 [ 23.267934] [] pppol2tp_release+0x239/0x2e0 [ 23.273895] [] sock_release+0x96/0x1c0 [ 23.279464] [] sock_close+0x16/0x20 [ 23.284744] [] __fput+0x263/0x700 [ 23.289855] [] ____fput+0x15/0x20 [ 23.289865] [] task_work_run+0x10c/0x180 [ 23.289874] [] exit_to_usermode_loop+0xfc/0x120 [ 23.289881] [] do_syscall_64+0x364/0x490 [ 23.289890] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 23.290006] 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 65 df c9 fd 4c 89 ea 48 b8 00 [ 23.290016] RIP [] l2tp_session_free+0x11c/0x200 [ 23.290019] RSP [ 23.290022] CR2: 0000000000000080 [ 23.293557] ---[ end trace 95ea7f73aed15ad4 ]--- [ 23.293561] Kernel panic - not syncing: Fatal exception [ 23.294035] Dumping ftrace buffer: [ 23.294039] (ftrace buffer empty) [ 23.294042] Kernel Offset: disabled [ 23.377005] Rebooting in 86400 seconds..