[....] Starting periodic command scheduler: cron[?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 16.541459] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 19.107247] random: sshd: uninitialized urandom read (32 bytes read) [ 19.366056] random: sshd: uninitialized urandom read (32 bytes read) [ 19.866868] random: sshd: uninitialized urandom read (32 bytes read) [ 25.290217] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.10.31' (ECDSA) to the list of known hosts. [ 30.708040] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 30.907713] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 30.916141] IP: [<ffffffff836bf9cc>] l2tp_session_free+0x11c/0x200 [ 30.922739] PGD 1c68a6067 [ 30.925397] PUD 1c90df067 PMD 0 [ 30.928906] [ 30.930539] Oops: 0002 [#1] PREEMPT SMP KASAN [ 30.935018] Dumping ftrace buffer: [ 30.938542] (ftrace buffer empty) [ 30.942238] Modules linked in: [ 30.945551] CPU: 1 PID: 3779 Comm: syz-executor640 Not tainted 4.9.119-g9dc978d #75 [ 30.953459] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 30.963287] task: ffff8801bca51800 task.stack: ffff8801ba020000 [ 30.969347] RIP: 0010:[<ffffffff836bf9cc>] [<ffffffff836bf9cc>] l2tp_session_free+0x11c/0x200 [ 30.978212] RSP: 0018:ffff8801ba027ca0 EFLAGS: 00010246 [ 30.983642] RAX: dffffc0000000000 RBX: ffff8801caa34280 RCX: 0000000000000000 [ 30.991054] RDX: 1ffff100393cdfa0 RSI: ffffffff836bf9a1 RDI: ffff8801c9e6fd00 [ 30.998312] RBP: ffff8801ba027cc0 R08: ffff8801bca520e8 R09: 0000000000000000 [ 31.005562] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801c9e6fb80 [ 31.012938] R13: ffff8801caa34288 R14: 0000000000000000 R15: ffffffff83015be0 [ 31.020193] FS: 00000000012f9880(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 [ 31.028398] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 31.034259] CR2: 0000000000000080 CR3: 00000001c937b000 CR4: 00000000001606f0 [ 31.041503] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 31.048747] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 31.055986] Stack: [ 31.058107] ffff8801ba492a80 ffff8801caa34280 ffff8801ba492e50 ffff8801ba492d58 [ 31.066098] ffff8801ba027ce8 ffffffff836c72b2 ffff8801ba492ec0 ffff8801ba492a80 [ 31.074080] ffffffff836c71e0 ffff8801ba027d20 ffffffff830230f5 ffff8801ba492ec0 [ 31.082066] Call Trace: [ 31.084633] [<ffffffff836c72b2>] pppol2tp_session_destruct+0xd2/0x110 [ 31.091361] [<ffffffff836c71e0>] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 31.097655] [<ffffffff830230f5>] __sk_destruct+0x55/0x590 [ 31.103252] [<ffffffff83015be0>] ? sock_release+0x1c0/0x1c0 [ 31.109019] [<ffffffff8302ab83>] sk_destruct+0x63/0x80 [ 31.114354] [<ffffffff8302abef>] __sk_free+0x4f/0x220 [ 31.119603] [<ffffffff8302adeb>] sk_free+0x2b/0x40 [ 31.124594] [<ffffffff836ca5b9>] pppol2tp_release+0x239/0x2e0 [ 31.130538] [<ffffffff83015ab6>] sock_release+0x96/0x1c0 [ 31.136096] [<ffffffff83015bf6>] sock_close+0x16/0x20 [ 31.141355] [<ffffffff81578693>] __fput+0x263/0x700 [ 31.146432] [<ffffffff81578bb5>] ____fput+0x15/0x20 [ 31.151551] [<ffffffff8119838c>] task_work_run+0x10c/0x180 [ 31.157247] [<ffffffff8100559c>] exit_to_usermode_loop+0xfc/0x120 [ 31.163738] [<ffffffff810064d4>] do_syscall_64+0x364/0x490 [ 31.169427] [<ffffffff839fccd3>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 31.176320] 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 <f0> 41 ff 8e 80 00 00 00 74 69 e8 f5 f0 c9 fd 4c 89 ea 48 b8 00 [ 31.203305] RIP [<ffffffff836bf9cc>] l2tp_session_free+0x11c/0x200 [ 31.209822] RSP <ffff8801ba027ca0> [ 31.213424] CR2: 0000000000000080 [ 31.217364] ---[ end trace 157b910f98bc1a4d ]--- [ 31.222186] Kernel panic - not syncing: Fatal exception [ 31.227946] Dumping ftrace buffer: [ 31.231472] (ftrace buffer empty) [ 31.235159] Kernel Offset: disabled [ 31.238760] Rebooting in 86400 seconds..