[....] 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[ 13.685600] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 16.627560] random: sshd: uninitialized urandom read (32 bytes read) [ 16.815354] random: sshd: uninitialized urandom read (32 bytes read) [ 17.301364] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.3' (ECDSA) to the list of known hosts. [ 23.085069] urandom_read: 1 callbacks suppressed [ 23.085073] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 23.292439] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 23.300682] IP: [] l2tp_session_free+0x11c/0x200 [ 23.307108] PGD 1cb0f9067 [ 23.309756] PUD 1cb23a067 PMD 0 [ 23.313266] [ 23.314888] Oops: 0002 [#1] PREEMPT SMP KASAN [ 23.319405] Dumping ftrace buffer: [ 23.322922] (ftrace buffer empty) [ 23.326622] Modules linked in: [ 23.329920] CPU: 0 PID: 3796 Comm: syz-executor246 Not tainted 4.9.124-g6a1b592 #82 [ 23.337710] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 23.347046] task: ffff8801b7fe3000 task.stack: ffff8801b5f38000 [ 23.353084] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 23.361951] RSP: 0018:ffff8801b5f3fc98 EFLAGS: 00010246 [ 23.367391] RAX: dffffc0000000000 RBX: ffff8801cb320f00 RCX: 0000000000000000 [ 23.374644] RDX: 1ffff10036ca76b0 RSI: ffffffff836c4711 RDI: ffff8801b653b580 [ 23.381901] RBP: ffff8801b5f3fcb8 R08: ffff8801b7fe38e8 R09: 0000000000000000 [ 23.389151] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801b653b400 [ 23.396399] R13: ffff8801cb320f08 R14: 0000000000000000 R15: 0000000000000000 [ 23.403649] FS: 0000000000c57880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 23.411874] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 23.417737] CR2: 0000000000000080 CR3: 00000001c9c21000 CR4: 00000000001606f0 [ 23.425006] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 23.432257] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 23.439504] Stack: [ 23.441636] ffff8801b5cbaa80 ffff8801cb320f00 ffff8801b5cbae50 ffff8801b5cbad58 [ 23.449637] ffff8801b5f3fce0 ffffffff836cc022 ffff8801b5cbaec0 ffff8801b5cbaa80 [ 23.457644] ffffffff836cbf50 ffff8801b5f3fd18 ffffffff830281f5 ffff8801b5cbaec0 [ 23.465645] Call Trace: [ 23.468217] [] pppol2tp_session_destruct+0xd2/0x110 [ 23.474867] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 23.481182] [] __sk_destruct+0x55/0x590 [ 23.486793] [] sk_destruct+0x63/0x80 [ 23.492146] [] __sk_free+0x4f/0x220 [ 23.497403] [] sk_free+0x2b/0x40 [ 23.502400] [] pppol2tp_release+0x239/0x2e0 [ 23.508363] [] __sock_release+0xd7/0x260 [ 23.514061] [] ? __sock_release+0x260/0x260 [ 23.520009] [] sock_close+0x19/0x20 [ 23.525266] [] __fput+0x263/0x700 [ 23.530351] [] ____fput+0x15/0x20 [ 23.535437] [] task_work_run+0x10c/0x180 [ 23.541128] [] exit_to_usermode_loop+0xfc/0x120 [ 23.547422] [] do_syscall_64+0x364/0x490 [ 23.553112] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 23.560011] 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 a5 c5 c9 fd 4c 89 ea 48 b8 00 [ 23.586990] RIP [] l2tp_session_free+0x11c/0x200 [ 23.593510] RSP [ 23.597116] CR2: 0000000000000080 [ 23.600994] ---[ end trace 2162fe3c3b9014d0 ]--- [ 23.605792] Kernel panic - not syncing: Fatal exception [ 23.611467] Dumping ftrace buffer: [ 23.614984] (ftrace buffer empty) [ 23.618671] Kernel Offset: disabled [ 23.622271] Rebooting in 86400 seconds..