StdLib/BsdSocketLib: Fix minor memory leak by freeing rrecp on error …

…return.

The error return is triggered by one of two conditions:
  1.  rrecp is NULL (calloc failed)
  2.  strdup(dname) returns NULL

Previously, the function just returned NULL.  This patch adds a call to
free rrecp before returning NULL.  Since the free() function will properly
do nothing when called with a NULL parameter, it is not necessary to
separate the two tests into separate if clauses.

Reported-by: Colin King <colin.king@canonical.com>

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Daryl McDaniel <edk2-lists@mc2research.org>
Reviewed-by: Jaben Carsey <jaben.carsey@intel.com>

StdLib/BsdSocketLib/res_mkupdate.c

@@ -438,8 +438,10 @@ res_mkupdrec(int section, const char *dname,
          u_int class, u_int type, u_long ttl) {
     ns_updrec *rrecp = (ns_updrec *)calloc(1, sizeof(ns_updrec));
 
-    if (!rrecp || !(rrecp->r_dname = strdup(dname)))
+    if (!rrecp || !(rrecp->r_dname = strdup(dname))) {
+        free(rrecp);
         return (NULL);
+    }
     rrecp->r_class = (u_int16_t)class;
     rrecp->r_type = (u_int16_t)type;
     rrecp->r_ttl = (u_int32_t)ttl;