[socket] Fix bad parameter passed to select (#4390)

If fd is equals to FD_SETSIZE, then we pass (FD_SETSIZE + 1) as first parameter to select, making it return EINVAL.

diff --git a/mono/utils/mono-poll.c b/mono/utils/mono-poll.c
index 74d39ced0c0292f1c365af67aa5ad8fc8351e9a0..d81b4eb9168f050626d4afd5ab31628fd5d061fa 100755 (executable)
--- a/mono/utils/mono-poll.c
+++ b/mono/utils/mono-poll.c
@@ -60,7 +60,7 @@ mono_poll (mono_pollfd *ufds, unsigned int nfds, int timeout)
                        return 1;
                }
 #else
-               if (fd > FD_SETSIZE) {
+               if (fd >= FD_SETSIZE) {
                        ufds [i].revents = MONO_POLLNVAL;
                        return 1;
                }