Sort Objects() in O(n log n) to avoid xref DoS#12
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Objects() insertion-sorted every xref entry (commented "small dataset"), but the entry count is attacker-controlled — a crafted xref stream with millions of entries made it O(n^2) and could hang for minutes. Use sort.Slice (O(n log n)); the ascending iteration order is unchanged. Test: TestObjectsIteratorSortedOrder.
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That is the last issue I found in the codebase at all, the next ones will be just test coverage. |
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The one item from my own earlier review that slipped through (the external security review didn't flag it).
Reader.Objects()insertion-sorted every xref entry, with a comment assuming a "small dataset" — but the entry count is attacker-controlled. A crafted xref stream packs millions of entries into a few MB (decoded cap 16 MiB ÷ ~4 B/entry ≈ 4M), making the sort O(n²) → ~10¹³ comparisons → a minutes-long CPU hang (DoS). The fuzzer missed it because fuzz inputs are tiny, sonstays small.Fix:
sort.Slice(O(n log n)). Iteration order is unchanged (ascending by object number, then generation).TestObjectsIteratorSortedOrderguards that the sort still yields ascending order — the xref map's random iteration order means the sort is what produces it, so a wrong comparator would fail it. The complexity improvement itself is by construction.go test -race ./...passes;go vetandgofmtclean.