fix: bounds-check hexdiff() offset-skip loop to prevent IndexError#5036
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citizen204 wants to merge 1 commit into
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fix: bounds-check hexdiff() offset-skip loop to prevent IndexError#5036citizen204 wants to merge 1 commit into
citizen204 wants to merge 1 commit into
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hexdiff() raised IndexError when the difflib alignment produced a 16-byte display row that was entirely a gap on one side. The loop that skips leading empty cells to compute the row offset had no bounds check and walked off the end of the row. Fixes secdev#5034 AI-Assisted: yes (Claude Sonnet 5)
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Summary
hexdiff()raisesIndexError: list index out of rangewhen the difflib alignment (algo='difflib') produces a 16-byte display row that is entirely a "gap" on one side (a run of >=16 aligned insertions/deletions). The loop that skips leading empty cells to compute the row's starting offset had no bounds check and walked off the end of the row.Fixes #5034
Changes
scapy/utils.py: addedj < len(linex)/j < len(liney)bounds checks to the two offset-skipwhileloops inhexdiff(), so the loop stops once it reaches the end of a fully-gapped row instead of indexing past it.test/regression.uts: added a regression test using the minimal reproduction from the issue (hexdiff(b"B"*9 + b"\x08", b"A" + b"\x08" + b"A"*23, algo="difflib")), which previously raisedIndexErrorand now completes without crashing.AI-Assisted: yes (Claude Sonnet 5)