Missing checking the lsa_length in ospf

[Mingwei Zheng]

Hi,

I am doing testing work on network protocols and here is one possible issue I 
noticed in OSPF.

I noticed that you have checked the length of lsa in your function 
ospf_dump_lsupd in lsupd.c 
<https://gitlab.nic.cz/labs/bird/-/blob/master/proto/ospf/lsupd.c>:

   if (((lsa_len % 4) != 0) || (lsa_len <= sizeof(struct ospf_lsa_header)))
      goto invalid;
However in the other packet types, like LSACK and LSREQ, I didn’t see similar 
checking. I am worrying about whether this would be an issue.
I would really appreciate it if anyone can have a look at it. Thank you!

Best
Mingwei