[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 12.741952] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. [ 13.092816] random: sshd: uninitialized urandom read (32 bytes read) [ 13.299072] random: sshd: uninitialized urandom read (32 bytes read) Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 14.471717] random: sshd: uninitialized urandom read (32 bytes read) [ 14.617527] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.37' (ECDSA) to the list of known hosts. [ 20.150684] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 20.354124] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 20.362362] IP: [] l2tp_session_free+0x11c/0x200 [ 20.368787] PGD 1be99d067 [ 20.371426] PUD 1bf4ce067 PMD 0 [ 20.374912] [ 20.376530] Oops: 0002 [#1] PREEMPT SMP KASAN [ 20.381205] Dumping ftrace buffer: [ 20.384717] (ftrace buffer empty) [ 20.388398] Modules linked in: [ 20.391705] CPU: 0 PID: 3753 Comm: syz-executor840 Not tainted 4.9.113-g9905591 #14 [ 20.399474] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 20.408807] task: ffff8801bd176000 task.stack: ffff8801bba60000 [ 20.414847] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 20.423695] RSP: 0018:ffff8801bba67ca0 EFLAGS: 00010246 [ 20.429129] RAX: dffffc0000000000 RBX: ffff8801ca692c80 RCX: 0000000000000000 [ 20.436382] RDX: 1ffff100393f5cd0 RSI: ffffffff836bcee1 RDI: ffff8801c9fae680 [ 20.443635] RBP: ffff8801bba67cc0 R08: ffff8801bd1768e8 R09: 0000000000000000 [ 20.450889] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801c9fae500 [ 20.458136] R13: ffff8801ca692c88 R14: 0000000000000000 R15: ffffffff83013be0 [ 20.465384] FS: 0000000000b66880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 20.473692] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 20.479552] CR2: 0000000000000080 CR3: 00000001c401b000 CR4: 00000000001606f0 [ 20.487410] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 20.495352] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 20.503524] Stack: [ 20.505659] ffff8801bbb31100 ffff8801ca692c80 ffff8801bbb314d0 ffff8801bbb313d8 [ 20.513708] ffff8801bba67ce8 ffffffff836c47f2 ffff8801bbb31540 ffff8801bbb31100 [ 20.521706] ffffffff836c4720 ffff8801bba67d20 ffffffff83021095 ffff8801bbb31540 [ 20.529722] Call Trace: [ 20.532296] [] pppol2tp_session_destruct+0xd2/0x110 [ 20.538937] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 20.545230] [] __sk_destruct+0x55/0x590 [ 20.550840] [] ? sock_release+0x1c0/0x1c0 [ 20.556610] [] sk_destruct+0x63/0x80 [ 20.561949] [] __sk_free+0x4f/0x220 [ 20.567198] [] sk_free+0x2b/0x40 [ 20.572191] [] pppol2tp_release+0x239/0x2e0 [ 20.578137] [] sock_release+0x96/0x1c0 [ 20.583648] [] sock_close+0x16/0x20 [ 20.588902] [] __fput+0x263/0x700 [ 20.593982] [] ____fput+0x15/0x20 [ 20.599069] [] task_work_run+0x10c/0x180 [ 20.604762] [] exit_to_usermode_loop+0xfc/0x120 [ 20.611052] [] do_syscall_64+0x364/0x490 [ 20.616738] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 20.623641] 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 55 1b ca fd 4c 89 ea 48 b8 00 [ 20.650629] RIP [] l2tp_session_free+0x11c/0x200 [ 20.657146] RSP [ 20.660758] CR2: 0000000000000080 [ 20.664619] ---[ end trace 5153ee299923984a ]--- [ 20.669397] Kernel panic - not syncing: Fatal exception [ 20.675277] Dumping ftrace buffer: [ 20.678791] (ftrace buffer empty) [ 20.682478] Kernel Offset: disabled [ 20.686078] Rebooting in 86400 seconds..