read: bound zstd-decompressed size to the declared size#951
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scadastrangelove wants to merge 1 commit into
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read: bound zstd-decompressed size to the declared size#951scadastrangelove wants to merge 1 commit into
scadastrangelove wants to merge 1 commit into
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CompressedData::decompress reserves try_reserve_exact(size) for the header-declared uncompressed size, but the Zstandard branch's read_to_end grows the buffer to the actual decoded length, ignoring that reservation (the Zlib branch stays bounded by its reserved capacity via decompress_vec). A section declaring a small ch_size but carrying a stream that expands to gigabytes therefore allocates the full decoded size before the trailing size != decompressed.len() check can reject it. Bound the zstd read to size (+1 so the existing size check still rejects an over-long stream), so the allocation can no longer exceed the declared size. Discovered by the rust-in-peace security pipeline (https://github.com/scadastrangelove/rust-in-peace/).
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Fixes #950.
The Zstandard branch of
CompressedData::decompressgrowsdecompressedpast thetry_reserve_exact(size)reservation that the Zlib branch respects (decompress_vecstays within its reserved capacity,read_to_enddoes not). So a section declaring a smallch_sizecan allocate the full decoded size of a large-expanding zstd stream before the trailingsize != decompressed.len()check rejects it.This bounds the zstd read to
size(plus one byte, so the existing size check still rejects an over-long stream), so the allocation can no longer exceed the declared uncompressed size.Verified against
main:cargo testpasses (25 lib + 7 integration);Discovered by the rust-in-peace security pipeline.