Cap DNS section counts to prevent oversized allocations#133
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Isusami wants to merge 1 commit intomasterking32:mainfrom
Open
Cap DNS section counts to prevent oversized allocations#133Isusami wants to merge 1 commit intomasterking32:mainfrom
Isusami wants to merge 1 commit intomasterking32:mainfrom
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Add maxSectionCount (256) guard in parseQuestions and parseResourceRecords to reject malformed packets with absurdly large QD/AN/NS/AR counts before allocating slices. Includes 6 new tests covering all section types for both ParsePacket and ParsePacketLite.
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Summary
Add a
maxSectionCount(256) guard to reject DNS packets with absurdly large section counts before allocating slices, preventing memory-based DoS.Changes
ErrSectionCountTooLargeerror andmaxSectionCount = 256constantparseQuestionsandparseResourceRecordsbefore slice allocationParsePacketandParsePacketLiteWhy
A malformed DNS packet can claim 65535 questions or resource records. Without a cap, the parser allocates a huge slice before discovering the data is truncated. The limit of 256 is well above any legitimate DNS packet while preventing abuse.
Test plan
go test -race ./internal/dnsparser/...-- all 30 tests pass (including 6 new), race-clean