From 23bd46bac652d9024230fe43d2da57821060a30e Mon Sep 17 00:00:00 2001
From: Eric Blankenhorn <eric@wolfssl.com>
Date: Thu, 25 Mar 2021 09:45:51 -0500
Subject: [PATCH] Sanity check sockfd

---
 src/wolfio.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/wolfio.c b/src/wolfio.c
index cff63d3e2..3a5677fe2 100644
--- a/src/wolfio.c
+++ b/src/wolfio.c
@@ -800,6 +800,11 @@ int wolfIO_Send(SOCKET_T sd, char *buf, int sz, int wrFlags)
         nfds = (int)sockfd + 1;
     #endif
 
+        if ((sockfd < 0) || (sockfd >= FD_SETSIZE)) {
+            WOLFSSL_MSG("socket fd out of FDSET range");
+            return -1;
+        }
+
         FD_ZERO(&rfds);
         FD_SET(sockfd, &rfds);
         wfds = rfds;