Guard against overflow in SubReadStream#128074
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Tagging subscribers to this area: @karelz, @dotnet/area-system-io-compression |
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Pull request overview
This PR hardens SubReadStream implementations used by ZIP and TAR readers by making the _endInSuperStream computation overflow-checked, preventing silent wraparound when startPosition + maxLength exceeds long.MaxValue.
Changes:
- Add
checked(startPosition + maxLength)when computing_endInSuperStreaminSystem.IO.Compression’sZipCustomStreams.SubReadStream. - Add the same checked arithmetic in
System.Formats.Tar’sSubReadStream.
Reviewed changes
Copilot reviewed 2 out of 2 changed files in this pull request and generated 4 comments.
| File | Description |
|---|---|
| src/libraries/System.IO.Compression/src/System/IO/Compression/ZipCustomStreams.cs | Adds overflow-checked end-position calculation for ZIP entry substreams. |
| src/libraries/System.Formats.Tar/src/System/Formats/Tar/SubReadStream.cs | Adds overflow-checked end-position calculation for TAR entry substreams. |
Comment on lines
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to
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| { | ||
| _startInSuperStream = startPosition; | ||
| _positionInSuperStream = startPosition; | ||
| _endInSuperStream = startPosition + maxLength; | ||
| _endInSuperStream = checked(startPosition + maxLength); | ||
| _superStream = superStream; |
| _startInSuperStream = startPosition; | ||
| _positionInSuperStream = startPosition; | ||
| _endInSuperStream = startPosition + maxLength; | ||
| _endInSuperStream = checked(startPosition + maxLength); |
Comment on lines
264
to
268
| { | ||
| _startInSuperStream = startPosition; | ||
| _positionInSuperStream = startPosition; | ||
| _endInSuperStream = startPosition + maxLength; | ||
| _endInSuperStream = checked(startPosition + maxLength); | ||
| _superStream = superStream; |
| _startInSuperStream = startPosition; | ||
| _positionInSuperStream = startPosition; | ||
| _endInSuperStream = startPosition + maxLength; | ||
| _endInSuperStream = checked(startPosition + maxLength); |
This was referenced May 12, 2026
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iremyux
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May 12, 2026
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iremyux
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LGTM, would adding some tests be useful in this case?
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