`zlib.crc32_combine()` hangs on a negative length and `adler32_combine()` returns rubbish
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@StanFromIreland is already working on this.
Since Aug 21, 2026.
3.15
3.16
extension-modules
type-bug
- Dominant language
- Python
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Description
Bug report
Bug description:
From the manual:
adler32_combine: Iflen2is negative, the result has no meaning or utility.
crc32_combine:len2must be non-negative.
To reproduce run:
$ python3.15 -c "import zlib; zlib.crc32_combine(0, 0, -5)"
which hangs due to a loop in zlib. And,
$ python3.15 -c "import zlib; print(zlib.adler32_combine(0, 0, -5))"
4294967295
which is rubbish.
CPython versions tested on:
CPython main branch
Operating systems tested on:
No response
Linked PRs
- gh-156181
- gh-156239
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