xenbus: reject unterminated directory replies

xenbus: reject unterminated directory replies

split_strings() walks each directory entry with strlen(). Although the
transport adds a terminator after the reply buffer, a malformed reply
without a final NUL inside its advertised length would let that walk
cross the protocol payload boundary.

Reject such replies before counting the strings. Report the protocol
violation once and return -EIO to the caller.

Signed-off-by: Yousef Alhouseen <alhouseenyousef@gmail.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Message-ID: <20260626223738.43742-1-alhouseenyousef@gmail.com>