staging: lustre: lustre: ptlrpc: sec_config.c: Fix for possible null pointer dereference

There is otherwise a risk of a possible null pointer dereference.

Was largely found by using a static code analysis program called cppcheck.
Signed-off-by: Rickard Strandqvist <rickard_strandqvist@spectrumdigital.se>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/lustre/lustre/ptlrpc/sec_config.c

@@ -745,11 +745,13 @@ void sptlrpc_conf_log_update_begin(const char *logname)
 	mutex_lock(&sptlrpc_conf_lock);
 
 	conf = sptlrpc_conf_get(fsname, 0);
-	if (conf && conf->sc_local) {
-		LASSERT(conf->sc_updated == 0);
-		sptlrpc_conf_free_rsets(conf);
+	if (conf) {
+		if(conf->sc_local) {
+			LASSERT(conf->sc_updated == 0);
+			sptlrpc_conf_free_rsets(conf);
+		}
+		conf->sc_modified = 0;
 	}
-	conf->sc_modified = 0;
 
 	mutex_unlock(&sptlrpc_conf_lock);
 }