[BUG] nbd-server: Remote stack-based buffer overflow

[Dialluvioso <dialluvioso@protonmail.com>]

There is a remote exploitable stack-based buffer overflow in line 2299 `handle_info` (`nbd-server.c`), fields `len` and `namelen` aren't properly checked therefore `socked_read` will overflow local buffer `buf` (max size 1024 bytes).

For reproducing the issue, you only need to perform the negotiation of the protocol and send a `NB_OPT_INFO` or `NBD_OPT_GO` request with a malformed `len`.