ITS#7270 Protect accesses to ldap_int_hostname with a mutex.

Not protecting the accesses to ldap_int_hostname could lead to a double
free.

libraries/libldap/init.c

@@ -642,6 +642,7 @@ void ldap_int_initialize( struct ldapoptions *gopts, int *dbglvl )
 
 #if defined(HAVE_TLS) || defined(HAVE_CYRUS_SASL)
 	{
+		LDAP_MUTEX_LOCK( &ldap_int_hostname_mutex );
 		char	*name = ldap_int_hostname;
 
 		ldap_int_hostname = ldap_pvt_get_fqdn( name );
@@ -649,6 +650,7 @@ void ldap_int_initialize( struct ldapoptions *gopts, int *dbglvl )
 		if ( name != NULL && name != ldap_int_hostname ) {
 			LDAP_FREE( name );
 		}
+		LDAP_MUTEX_UNLOCK( &ldap_int_hostname_mutex );
 	}
 #endif
 

libraries/libldap/ldap-int.h

@@ -488,6 +488,7 @@ struct ldap {
 
 #ifdef LDAP_R_COMPILE
 LDAP_V ( ldap_pvt_thread_mutex_t ) ldap_int_resolv_mutex;
+LDAP_V ( ldap_pvt_thread_mutex_t ) ldap_int_hostname_mutex;
 
 #ifdef HAVE_CYRUS_SASL
 LDAP_V( ldap_pvt_thread_mutex_t ) ldap_int_sasl_mutex;

libraries/libldap/util-int.c

@@ -58,6 +58,7 @@ extern int h_errno;
 #else
 # include <ldap_pvt_thread.h>
   ldap_pvt_thread_mutex_t ldap_int_resolv_mutex;
+  ldap_pvt_thread_mutex_t ldap_int_hostname_mutex;
 
 # if (defined( HAVE_CTIME_R ) || defined( HAVE_REENTRANT_FUNCTIONS)) \
 	 && defined( CTIME_R_NARGS )
@@ -603,6 +604,8 @@ void ldap_int_utils_init( void )
 #endif
 	ldap_pvt_thread_mutex_init( &ldap_int_resolv_mutex );
 
+	ldap_pvt_thread_mutex_init( &ldap_int_hostname_mutex );
+
 #ifdef HAVE_CYRUS_SASL
 	ldap_pvt_thread_mutex_init( &ldap_int_sasl_mutex );
 #endif