mtree: access values before safety checks of variables

(cherry picked from commit 56d1d31)

src/modules/mtree/mtree.c

@@ -985,12 +985,13 @@ int mt_rpc_add_tvalues(rpc_t* rpc, void* ctx, m_tree_t *pt, str *tomatch)
 	mt_node_t *itn;
 	mt_is_t *tvalues;
 	void *vstruct = NULL;
-	str prefix = *tomatch;
+	str prefix = STR_NULL;
 
 	if (pt == NULL || tomatch == NULL || tomatch->s == NULL) {
 		LM_ERR("bad parameters\n");
 		return -1;
 	}
+	prefix = *tomatch;
 
 	l = 0;
 	itn = pt->head;
@@ -1051,7 +1052,7 @@ int mt_rpc_match_prefix(rpc_t* rpc, void* ctx, m_tree_t *it,
 	is_t *tvalue;
 	mt_dw_t *dw;
 	int tprefix_len = 0;
-	str prefix = *tomatch;
+	str prefix = STR_NULL;
 	void *vstruct = NULL;
 
 #define MT_MAX_DST_LIST	64
@@ -1063,6 +1064,7 @@ int mt_rpc_match_prefix(rpc_t* rpc, void* ctx, m_tree_t *it,
 		LM_ERR("bad parameters\n");
 		return -1;
 	}
+	prefix = *tomatch;
 
 	if (rpc->add(ctx, "S", &it->tname) < 0) {
 		rpc->fault(ctx, 500, "Internal error adding tname");

src/modules/mtree/mtree_mod.c

@@ -761,16 +761,20 @@ static int mt_load_db_trees()
 		{
 			/* check for NULL values ?!?! */
 			tname.s = (char*)(RES_ROWS(db_res)[i].values[0].val.string_val);
-			tname.len = strlen(tname.s);
-
 			tprefix.s = (char*)(RES_ROWS(db_res)[i].values[1].val.string_val);
-			tprefix.len = strlen(tprefix.s);
-
 			tvalue.s = (char*)(RES_ROWS(db_res)[i].values[2].val.string_val);
+
+			if(tprefix.s==NULL || tvalue.s==NULL || tname.s==NULL)
+			{
+				LM_ERR("Error - null fields in db\n");
+				continue;
+			}
+
+			tname.len = strlen(tname.s);
+			tprefix.len = strlen(tprefix.s);
 			tvalue.len = strlen(tvalue.s);
 
-			if(tprefix.s==NULL || tvalue.s==NULL || tname.s==NULL ||
-					tprefix.len<=0 || tvalue.len<=0 || tname.len<=0)
+			if(tname.len<=0 || tprefix.len<=0 || tvalue.len<=0)
 			{
 				LM_ERR("Error - bad values in db\n");
 				continue;