[zstd][#60] Add decompression size sanity Check#115
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Fix #60 Before we were blindly trusting the data returned by ZSTD_getDecompressedSize. This mean with a specifically crafter payload, we would try to allocate a lot of memory resulting in potential DOS. Now set a sane limit and fall back to streaming
Since zstd 1.3.0+, the zstd header has size hint so you should be able to decompress the first time directly with that hint OR directly fallback to streaming. No need to try 3 times
kevinconaway
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Apr 14, 2022
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This was referenced Jun 2, 2022
Viq111
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Contrary to Decompress, bulk.Decompress does not retry with stream decompression on failing to Decompress. #115 introduced preventing to allocate too big buffers when the input zstd header was malicious. This had the side-effect that for highly compressed payloads (> 10x), the dst buffer was still resized and would fail. This fixes the issue and adds a test
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Fix #60 (see for full description).
Previously, we were trusting the input from the zstd header to allocate the memory on
DecompressAPI. This meant a carefully crafted payload could make the zstd wrapper allocates an arbitrary size:After this fix, we correctly don't allocate too much.
The main part of the change is at: 30c4b29#diff-fc46d6feefba07384476b9d2f5a4ae18d6f7322dcd684c388ebe1b2b8d19d394R55-R74
We now basically allocate up to:
min(ZSTD_getFrameContentSize(), max(1MB, 10*input_size))