gh-153570: Fix use-after-free in bytearray.take_bytes() with a reentrant __index__#153572
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gh-153570: Fix use-after-free in bytearray.take_bytes() with a reentrant __index__#153572tonghuaroot wants to merge 1 commit into
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…reentrant __index__ bytearray.take_bytes() cached the size before the argument's __index__ call and used it for the bounds check and the buffer reads, so an __index__ that resizes the bytearray left it reading freed memory. Re-read the size after __index__, matching bytearray.__setitem__ (pythonGH-91153).
cmaloney
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Jul 11, 2026
cmaloney
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I don't like that during take_bytes() the byterray is resizable... but critical section doesn't prevent same thread mutation of the object.
This looks like a good fix for the current state
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bytearray.take_bytes()used the size cached before the argument's__index__call for its bounds check andbuffer reads, so an
__index__that resizes the bytearray left it reading freed memory. Re-read the size after__index__, likebytearray.__setitem__(GH-91153).