fix: Ensure buffer space before reading in Decompress method#127105
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pumpkin-bit wants to merge 6 commits intodotnet:mainfrom
Open
fix: Ensure buffer space before reading in Decompress method#127105pumpkin-bit wants to merge 6 commits intodotnet:mainfrom
pumpkin-bit wants to merge 6 commits intodotnet:mainfrom
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Tagging subscribers to this area: @karelz, @dotnet/area-system-io-compression |
This was referenced Apr 18, 2026
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Thank you. Can you please also add a test that covers the described case?
…Zstandard/ZstandardStream.Decompress.cs Co-authored-by: Miha Zupan <mihazupan.zupan1@gmail.com>
…Zstandard/ZstandardStream.Decompress.cs Co-authored-by: Miha Zupan <mihazupan.zupan1@gmail.com>
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@dotnet-policy-service agree |
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done added a test case for ZstandardStream. |
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Did you check that the test fails before the fix in this PR? |
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Yes, I checked using a test to simulate the situation with and without my fix. Without the fix, the decompressor caught an exception. With my fix, the buffer moved correctly without errors. |
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The essence of the bug:
During decompression, a portion of compressed data ends exactly at the boundary of a 64 kb buffer, and the remaining bytes, not yet decompressed by the decoder, are waiting for the next portion, resulting in a exception. The buffer is physically full, and AvailableSpan returns an empty fragment,
Span<byte>empty reading from the file into an empty Span returns 0 bytes read.Solution:
Checks have been added to the main Read and ReadAsync loops. If AvailableLength is zero, we force a call to
_buffer.EnsureAvailableSpace(1);.the bytes are shifted to the beginning of the array, the read is released, and the stream then reads new data.