cpython/Lib/zipfile
Miss Islington (bot) 09a2e7e667
[3.12] gh-156002: Bound zipfile decompression for bzip2/LZMA/Zstandard (GH-156003) (GH-156362) (#156739)
* gh-156002: Bound zipfile decompression for bzip2/LZMA/Zstandard (GH-156003) (GH-156362)

Patch by @tonghuaroot.

zipfile.ZipExtFile._read1() bounds the output of each decompress() call
for DEFLATE members by passing a max_length to zlib, but for bzip2, LZMA,
and Zstandard members it called decompress() with no bound. A whole
compressed chunk was therefore expanded into a single allocation before
the data[:self._left] clip ran, so a consumer that deliberately reads in
small chunks to limit memory (for example zf.open(name).read(8192)) was
silently unprotected for non-DEFLATE members. A small, spec-conformant
archive member declaring a large uncompressed size could drive multi-GB
peak memory.

_read1() now passes a per-call bound to the non-DEFLATE decompress()
(mirroring the DEFLATE branch) and drains the decompressor's internal
buffer across calls by checking needs_input before reading more
compressed input. zipfile's LZMADecompressor wrapper forwards max_length
and exposes needs_input so the bound also holds for LZMA members.

(cherry picked from commit f897dbf2f3)
(cherry picked from commit 1b424c0178)

* gh-156002: Keep reading through monkey-patched zipfile decompressors (GH-157180) (GH-157557)

(cherry picked from commit f507e6946a)

Co-authored-by: Petr Viktorin <encukou@gmail.com>
Co-authored-by: tonghuaroot <tonghuaroot@gmail.com>
Co-authored-by: rasmusfaber <rfaber@gmail.com>
2026-09-30 22:55:10 +02:00
..
_path [3.12] gh-126565: Skip zipfile.Path.exists check in write mode (GH-126576) (#126643) 2024-11-10 15:14:48 +00:00
__init__.py [3.12] gh-156002: Bound zipfile decompression for bzip2/LZMA/Zstandard (GH-156003) (GH-156362) (#156739) 2026-09-30 22:55:10 +02:00
__main__.py [3.12] gh-112578: Fix RuntimeWarning when running zipfile (GH-112579) (GH-112646) 2023-12-03 11:41:50 +00:00