Validate LZ41 footer fields before decompression#399
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The decompressor read numOffsets, blockSize, and uncompressedSize from the compressed file footer with no validation, allowing a crafted LZ41 file to cause an OOM crash (numOffsets set to INT_MAX allocates ~8 GB), a DivideByZeroException (blockSize = 0), or an IndexOutOfRangeException (numOffsets smaller than the number of blocks the data requires). Adds four guards in LZ41_Stream_Decompress: - numOffsets must be > 0 and fit within the file (prevents OOM and integer overflow in the offset table seek calculation) - footer-supplied uncompressedSize must be > 0 - blockSize must be > 0 (prevents divide-by-zero) - endBlock must be < numOffsets before the decode loop (prevents the offsets[currentBlock+1] out-of-bounds access on the last iteration) Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Shivansps
approved these changes
May 6, 2026
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Things still work as expected |
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The decompressor read numOffsets, blockSize, and uncompressedSize from the compressed file footer with no validation, allowing a crafted LZ41 file to cause an OOM crash (numOffsets set to INT_MAX allocates ~8 GB), a DivideByZeroException (blockSize = 0), or an IndexOutOfRangeException (numOffsets smaller than the number of blocks the data requires).
Adds four guards in LZ41_Stream_Decompress: