BUG#30385: Server crash when deleting with ORDER BY and LIMIT

in get_index_for_order(), don't walk over the end of the index key parts
when matching index description and needed ordering.

mysql-test/r/delete.result

@@ -193,4 +193,15 @@ select @a;
 @a
 1
 drop table t1;
+CREATE TABLE t1 (
+`date` date ,
+`time` time ,
+`seq` int(10) unsigned NOT NULL auto_increment,
+PRIMARY KEY  (`seq`),
+KEY `seq` (`seq`),
+KEY `time` (`time`),
+KEY `date` (`date`)
+);
+DELETE FROM t1 ORDER BY date ASC, time ASC LIMIT 1;
+drop table t1;
 End of 4.1 tests

mysql-test/t/delete.test

@@ -184,4 +184,17 @@ delete from t1 where (@a:= f1) order by f1 limit 1;
 select @a;
 drop table t1;
 
+# BUG#30385 "Server crash when deleting with order by and limit"
+CREATE TABLE t1 (
+  `date` date ,
+  `time` time ,
+  `seq` int(10) unsigned NOT NULL auto_increment,
+  PRIMARY KEY  (`seq`),
+  KEY `seq` (`seq`),
+  KEY `time` (`time`),
+  KEY `date` (`date`)
+);
+DELETE FROM t1 ORDER BY date ASC, time ASC LIMIT 1;
+drop table t1;
+
 --echo End of 4.1 tests

sql/opt_range.cc

@@ -825,6 +825,7 @@ uint get_index_for_order(TABLE *table, ORDER *order, ha_rows limit)
     if (!(table->keys_in_use_for_query.is_set(idx)))
       continue;
     KEY_PART_INFO *keyinfo= table->key_info[idx].key_part;
+    uint n_parts=  table->key_info[idx].key_parts;
     uint partno= 0;
     
     /* 
@@ -834,7 +835,7 @@ uint get_index_for_order(TABLE *table, ORDER *order, ha_rows limit)
     */
     if (!(table->file->index_flags(idx, 0, 1) & HA_READ_ORDER))
       continue;
-    for (ord= order; ord; ord= ord->next, partno++)
+    for (ord= order; ord && partno < n_parts; ord= ord->next, partno++)
     {
       Item *item= order->item[0];
       if (!(item->type() == Item::FIELD_ITEM &&