1668 CVE 2011-3508 (ldap format string issues)

*** 19,28 ****
--- 19,29 ----
   * CDDL HEADER END
   */
  
  /*
   * Copyright (c) 2007, 2010, Oracle and/or its affiliates. All rights reserved.
+  * Copyright 2011 Nexenta Systems, Inc. All rights reserved.
   */
  
  /*
   * native LDAP related utility routines
   */
*** 145,159 ****
--- 146,177 ----
  int
  merge_SSD_filter(const ns_ldap_search_desc_t *desc,
          char **realfilter, const void *userdata)
  {
          int     len;
+         char *checker;
+ 
          if (realfilter == NULL)
                  return (NS_LDAP_INVALID_PARAM);
          *realfilter = NULL;
          if (desc == NULL || desc->filter == NULL || userdata == NULL)
                  return (NS_LDAP_INVALID_PARAM);
+ 
+         /* Parameter check.  We only want one %s here, otherwise bail. */
+         len = 0;        /* Reuse 'len' as "Number of %s hits"... */
+         checker = (char *)userdata;
+         do {
+                 checker = strchr(checker, '%');
+                 if (checker != NULL) {
+                         if (len > 0 || *(checker + 1) != 's')
+                                 return (NS_LDAP_INVALID_PARAM);
+                         len++;  /* Got our %s. */
+                         checker += 2;
+                 } else if (len != 1)
+                         return (NS_LDAP_INVALID_PARAM);
+         } while (checker != NULL);
+ 
          len = strlen(userdata) + strlen(desc->filter) + 1;
          *realfilter = (char *)malloc(len);
          if (*realfilter == NULL)
                  return (NS_LDAP_MEMORY);
          (void) sprintf(*realfilter, (char *)userdata, desc->filter);