From 9ebe27e18d0f2bd20865027d838dcacb6891d1f6 Mon Sep 17 00:00:00 2001
From: Christian Grothoff <christian@grothoff.org>
Date: Sat, 7 Mar 2020 17:09:22 +0100
Subject: check for socket validity

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

diff --git a/src/microhttpd/mhd_sockets.c b/src/microhttpd/mhd_sockets.c
index a52d5eb5..31b53e1e 100644
--- a/src/microhttpd/mhd_sockets.c
+++ b/src/microhttpd/mhd_sockets.c
@@ -505,6 +505,11 @@ MHD_socket_cork_ (MHD_socket sock,
   const MHD_SCKT_OPT_BOOL_ on_val = 1;
 
   /* Disable extra buffering */
+  if (MHD_INVALID_SOCKET == sock)
+  {
+    errno = EBADF;
+    return 0; /* failed */
+  }
   if (0 != setsockopt (sock,
                        IPPROTO_TCP,
                        MHD_TCP_CORK_NOPUSH,
-- 
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