fix[pack]: Don't decompress the delta when decompressing base objects. #2345
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It was already decompressed on line 285, so attempting to decompress it again turns the delta stream into garbage. Unfortunately I don't know enough about the git file format to make a test, the best I was able to do was to compare it to a reference implementation and see what was going wrong. Fixes GitoxideLabs#2344
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Pull request overview
This PR fixes a buffer corruption bug in pack file delta resolution where decompressing a base object would overwrite already-decompressed delta instructions. The issue was discovered when attempting to read a specific object from the Chromium repository (issue #2344).
Key Changes
- Fixed buffer slice calculation when decompressing base objects to prevent corruption of delta instruction data
- The fix restricts decompression output to only the portion of the buffer designated for base object data, excluding the delta instructions area
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Thanks so much for digging into this, and finding a solution. Just at a glance it makes perfect sense to bound the output buffer, to avoid the decompression to try to 'overshoot', which seems to happen now (with Admittedly, I couldn't try this against the …, and it succeeded. Beyond that, I think the test-suite would have caught it if this change was tuned to fixing exactly this one issue. |
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And I have created a patch-release for |
Co-authored-by: Byron <[email protected]>
- Generated pack-regression-*.pack with large base object (52KB) and delta chains - Updated regression test to use custom pack file - Added comprehensive documentation explaining test limitations - Test exercises the buffer bounding code path even though it doesn't fail without the fix (requires specific zlib-rs compression conditions like chromium repository) - Provides infrastructure for adding reproducing pack file in the future Co-authored-by: Byron <[email protected]>
0.64.1 contains GitoxideLabs/gitoxide#2345, which fixes an issue where it throws an error when attempting to unpack objects.
0.64.1 contains GitoxideLabs/gitoxide#2345, which fixes an issue where it throws an error when attempting to unpack objects.
0.64.1 contains GitoxideLabs/gitoxide#2345, which fixes an issue where it throws an error when attempting to unpack objects.
2 participants
It was already decompressed on line 285, so attempting to decompress it again turns the delta stream into garbage.
Unfortunately I don't know enough about the git file format to make a test, the best I was able to do was to compare it to a reference implementation and see what was going wrong.
Fixes #2344