[....] 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[ 14.170853] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 18.139646] random: sshd: uninitialized urandom read (32 bytes read) [ 18.305110] random: sshd: uninitialized urandom read (32 bytes read) [ 18.803522] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.9' (ECDSA) to the list of known hosts. [ 24.594308] urandom_read: 1 callbacks suppressed [ 24.594311] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 24.802386] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 24.810673] IP: [] l2tp_session_free+0x11c/0x200 [ 24.817103] PGD 1c6966067 [ 24.819745] PUD 1c8b51067 PMD 0 [ 24.823240] [ 24.824883] Oops: 0002 [#1] PREEMPT SMP KASAN [ 24.829364] Dumping ftrace buffer: [ 24.832894] (ftrace buffer empty) [ 24.836578] Modules linked in: [ 24.839876] CPU: 0 PID: 3673 Comm: syz-executor988 Not tainted 4.9.122-g54068d6 #78 [ 24.847640] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 24.857011] task: ffff8801c41c1800 task.stack: ffff8801c53f0000 [ 24.863040] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 24.871902] RSP: 0018:ffff8801c53f7ca0 EFLAGS: 00010246 [ 24.877335] RAX: dffffc0000000000 RBX: ffff8801cb582000 RCX: 0000000000000000 [ 24.884583] RDX: 1ffff100385c9300 RSI: ffffffff836c39a1 RDI: ffff8801c2e49800 [ 24.891833] RBP: ffff8801c53f7cc0 R08: ffff8801c41c20e8 R09: 0000000000000000 [ 24.899084] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801c2e49680 [ 24.906335] R13: ffff8801cb582008 R14: 0000000000000000 R15: ffffffff83019be0 [ 24.913592] FS: 0000000001383880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 24.921797] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 24.927657] CR2: 0000000000000080 CR3: 00000001ca71f000 CR4: 00000000001606f0 [ 24.934903] Stack: [ 24.937031] ffff8801c31b5500 ffff8801cb582000 ffff8801c31b58d0 ffff8801c31b57d8 [ 24.945031] ffff8801c53f7ce8 ffffffff836cb2b2 ffff8801c31b5940 ffff8801c31b5500 [ 24.953067] ffffffff836cb1e0 ffff8801c53f7d20 ffffffff830270f5 ffff8801c31b5940 [ 24.961068] Call Trace: [ 24.963636] [] pppol2tp_session_destruct+0xd2/0x110 [ 24.970279] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 24.976574] [] __sk_destruct+0x55/0x590 [ 24.982176] [] ? sock_release+0x1c0/0x1c0 [ 24.987956] [] sk_destruct+0x63/0x80 [ 24.993294] [] __sk_free+0x4f/0x220 [ 24.998561] [] sk_free+0x2b/0x40 [ 25.003554] [] pppol2tp_release+0x239/0x2e0 [ 25.009501] [] sock_release+0x96/0x1c0 [ 25.015027] [] sock_close+0x16/0x20 [ 25.020286] [] __fput+0x263/0x700 [ 25.025376] [] ____fput+0x15/0x20 [ 25.030457] [] task_work_run+0x10c/0x180 [ 25.036153] [] exit_to_usermode_loop+0xfc/0x120 [ 25.042448] [] do_syscall_64+0x364/0x490 [ 25.048148] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 25.055046] 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 95 d3 c9 fd 4c 89 ea 48 b8 00 [ 25.081900] RIP [] l2tp_session_free+0x11c/0x200 [ 25.088408] RSP [ 25.092005] CR2: 0000000000000080 [ 25.095566] ---[ end trace f7399beb53b2b71f ]--- [ 25.100314] Kernel panic - not syncing: Fatal exception [ 25.106021] Dumping ftrace buffer: [ 25.109544] (ftrace buffer empty) [ 25.113227] Kernel Offset: disabled [ 25.116827] Rebooting in 86400 seconds..