test: pin the negative-offset ReadBytes attack vector#75
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Follow-up to #74. The negative-count vector is directly tested; this adds the second documented vector — a negative offset with a compensating count (offset=-4, count=8) whose composite index offset+count-1=3 looked in range pre-fix, causing an OOB underflow read. The new independent start-offset check rejects it; this block makes that vector non-regressable. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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Follow-up to #74 applying the review suggestion: add a regression test for the second documented out-of-bounds vector — a negative offset with a compensating count (
offset=-4, count=8), whose composite indexoffset+count-1=3looked in range before the fix and read intodata-4(OOB underflow). The independent start-offset check added in #74 rejects it; this block makes that vector non-regressable. Test-only; verified passing underblitzcc -t.🤖 Generated with Claude Code