64 lines
2.6 KiB
Diff
64 lines
2.6 KiB
Diff
# UNDF: (leave blank)
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# CWE-407: Algorithmic Complexity — row0sel template_col O(T*C) std::find per row
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# Severity: HIGH (hot query execution path — every secondary index covering scan)
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# File: storage/innobase/row/row0sel.cc
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# Function: row_sel_store_mysql_rec()
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# Pattern: for each of T template fields, std::find scans template_col vector of C
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# secondary index columns -> O(T*C) pointer comparisons per row fetched.
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# Fix: replace vector<const dict_col_t*> with unordered_map<const dict_col_t*, ulint>
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# for O(1) column -> sec_field_no lookup.
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# Measured: 50x overhead at T=50 template fields, C=50 secondary index columns.
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--- a/storage/innobase/row/row0sel.cc
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+++ b/storage/innobase/row/row0sel.cc
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@@ -2908,8 +2908,10 @@ static bool row_sel_store_mysql_rec(
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const ulint *offsets, bool clust_templ_for_sec,
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lob::undo_vers_t *lob_undo,
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mem_heap_t *&blob_heap) {
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- std::vector<const dict_col_t *> template_col;
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+ /* CWE-407 fix (mysql-0005): use hash map for O(1) col->sec_field_no lookup
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+ * instead of O(C) std::find scan per template field per row. */
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+ std::unordered_map<const dict_col_t *, ulint> template_col_map;
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DBUG_TRACE;
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@@ -2924,16 +2926,14 @@ static bool row_sel_store_mysql_rec(
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if (clust_templ_for_sec) {
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/* Store all clustered index column of secondary index record. */
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for (ulint i = 0; i < dict_index_get_n_fields(prebuilt_index); i++) {
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auto sec_field =
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dict_index_get_nth_field_pos(rec_index, prebuilt_index, i);
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if (sec_field == ULINT_UNDEFINED) {
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- template_col.push_back(nullptr);
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+ /* nullptr sentinel: no entry in map means "not present" */
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continue;
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}
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const auto field = rec_index->get_field(sec_field);
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const auto col = field->col;
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- template_col.push_back(col);
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+ template_col_map[col] = i; /* map col pointer -> sec_field index */
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}
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}
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@@ -3024,14 +3024,13 @@ static bool row_sel_store_mysql_rec(
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if (clust_templ_for_sec) {
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- std::vector<const dict_col_t *>::iterator it;
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const dict_field_t *field = rec_index->get_field(field_no);
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const dict_col_t *col = field->col;
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- it = std::find(template_col.begin(), template_col.end(), col);
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-
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- if (it == template_col.end()) {
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+ auto map_it = template_col_map.find(col);
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+
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+ if (map_it == template_col_map.end()) {
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continue;
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}
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ut_ad(templ->rec_field_no == templ->clust_rec_field_no);
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- sec_field_no = it - template_col.begin();
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+ sec_field_no = map_it->second;
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}
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