49 lines
1.9 KiB
Diff
49 lines
1.9 KiB
Diff
# UNDF: UNDF-2026-000000161
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--- a/sql/sql_select.cc
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+++ b/sql/sql_select.cc
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@@ -29057,12 +29057,22 @@ setup_new_fields(THD *thd, List<Item> &fields,
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List<Item> &all_fields, ORDER *new_field)
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{
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Item **item;
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uint counter;
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enum_resolution_type not_used;
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DBUG_ENTER("setup_new_fields");
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thd->column_usage= MARK_COLUMNS_READ; // Not really needed, but...
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+ // CWE-407 fix (mariadb-0002): build name->item* map once before the loop.
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+ // find_item_in_list is O(S) per call; with N new fields this is O(N*S).
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+ // An upfront index reduces the loop body to O(1) for name-matched items.
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+ std::unordered_map<std::string, Item **> field_index;
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+ {
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+ List_iterator<Item> idx_it(fields);
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+ Item *idx_item;
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+ uint idx_pos = 0;
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+ while ((idx_item = idx_it++)) {
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+ if (idx_item->item_name.is_set())
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+ field_index[std::string(idx_item->item_name.ptr())] =
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+ fields.elem(idx_pos);
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+ ++idx_pos;
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+ }
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+ }
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for (; new_field ; new_field= new_field->next)
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{
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- if ((item= find_item_in_list(*new_field->item, fields, &counter,
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- IGNORE_ERRORS, ¬_used)))
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+ // Fast path: O(1) name lookup via pre-built index
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+ std::string lookup_name;
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+ if ((*new_field->item)->item_name.is_set())
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+ lookup_name = (*new_field->item)->item_name.ptr();
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+ auto fast = (!lookup_name.empty()) ? field_index.find(lookup_name)
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+ : field_index.end();
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+ if (fast != field_index.end()) {
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+ item = fast->second;
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+ } else if ((item= find_item_in_list(*new_field->item, fields, &counter,
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+ IGNORE_ERRORS, ¬_used))) {
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+ // fallback to linear scan for alias/table-qualified names
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+ } else {
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+ item = nullptr;
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+ }
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+ if (item)
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new_field->item=item; /* Change to shared Item */
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else
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{
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