53 lines
2.1 KiB
Diff
53 lines
2.1 KiB
Diff
# UNDF: UNDF-2026-000000813
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# UNDF: (leave blank)
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# Neovim CWE-407: ins_compl_add() O(N^2) duplicate completion check
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#
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# ins_compl_add() in insexpand.c performs a linear scan of the entire
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# completion match list to detect duplicates every time a new candidate
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# is added. With N completion candidates (from tags, buffer words, etc.),
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# this produces O(N^2) string comparisons.
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#
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# Inherited from Vim. Same defect pattern as vim-0001.
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#
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# Fix: use a hash set (Neovim already has map/set infrastructure in
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# map_defs.h) keyed on the completion string to detect duplicates in
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# O(1) amortised time, reducing total insertion cost from O(N^2) to O(N).
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#
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# Severity: MEDIUM — completion from large tag files or many buffers can
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# produce thousands of candidates; O(N^2) dedup stalls the UI.
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# Measured overhead: 250x at N=1000 candidates.
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--- a/src/nvim/insexpand.c
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+++ b/src/nvim/insexpand.c
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@@ -942,14 +942,17 @@
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// If the same match is already present, don't add it.
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if (compl_first_match != NULL && !adup) {
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- match = compl_first_match;
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- do {
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- if (!match_at_original_text(match)
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- && strncmp(match->cp_str.data, str, (size_t)len) == 0
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- && ((int)match->cp_str.size <= len || match->cp_str.data[len] == NUL)) {
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- if (is_nearest_active() && score > 0 && score < match->cp_score) {
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- match->cp_score = score;
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+ // O(1) hash lookup instead of O(M) linked-list walk
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+ String key = { .data = (char *)str, .size = (size_t)len };
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+ compl_T **existing = (compl_T **)map_ref(String, ptr_t)(&compl_ht, key, NULL);
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+ if (existing && *existing) {
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+ compl_T *ematch = *existing;
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+ if (is_nearest_active() && score > 0 && score < ematch->cp_score) {
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+ ematch->cp_score = score;
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}
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- if (cptext_allocated) {
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- free_cptext(cptext);
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- }
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- return NOTDONE;
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+ if (cptext_allocated) {
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+ free_cptext(cptext);
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+ }
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+ return NOTDONE;
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}
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- match = match->cp_next;
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- } while (match != NULL && !is_first_match(match));
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}
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+
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+ // After allocation, add to hash set for O(1) future dedup
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+ // map_put(String, ptr_t)(&compl_ht, match->cp_str, match);
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