smb: client: fix missing iov bounds check in parse_posix_sids()

In the Linux kernel, the following vulnerability has been resolved:

smb: client: fix missing iov bounds check in parse_posix_sids()

In parse_posix_sids(), sidsbuf_end is calculated using the server-supplied
out_len without being validated against the actual length of the received
iov (iov_len).

If a server provides an inflated out_len, sidsbuf_end will point past the
end of the iov. This defeats the bounds guards in posix_info_sid_size(),
allowing out-of-bounds reads into adjacent kernel memory.

Fix this by rejecting responses where the calculated sidsbuf_end would
exceed the received iov boundaries or cause pointer wraparound.