gh-151308: Avoid huge pre-allocation in wave.readframes() for crafted files#151487
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gh-151308: Avoid huge pre-allocation in wave.readframes() for crafted files#151487iamsharduld wants to merge 1 commit into
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…rafted files A WAV data chunk records its size in a 4-byte header field that is not validated against the data actually present in the file. A small, truncated, or maliciously crafted file could therefore claim a chunk of several gigabytes and make wave.Wave_read.readframes() pre-allocate that much memory via a single file.read(chunksize) call, leading to a MemoryError (or memory exhaustion) from a tiny input. When the underlying file is seekable, clamp each read in the internal _Chunk.read() to the number of bytes physically available, so we never allocate more than the file can actually provide. The data returned for valid files is unchanged.
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A WAV data chunk records its size in a 4-byte header field that is not
validated against the data actually present in the file. A small,
truncated, or maliciously crafted file can therefore claim a chunk of
several gigabytes and make
wave.Wave_read.readframes()pre-allocate thatmuch memory via a single
file.read(chunksize)call, leading to aMemoryError(or memory exhaustion) from a tiny input.When the underlying file is seekable, this clamps each read in the internal
_Chunk.read()to the number of bytes physically available, so we neverallocate more than the file can actually provide. The data returned for
valid files is unchanged.
Non-seekable streams retain the previous behaviour, since their size can't
be probed without buffering; the realistic attack vector is a
.wavfileon disk, which is fully covered.
wave.readframes()via Crafted Chunk Size #151308