gh-153570: Fix use-after-free in bytearray.take_bytes() with a reentrant __index__#153572
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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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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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Thanks @tonghuaroot for the PR, and @vstinner for merging it 🌮🎉.. I'm working now to backport this PR to: 3.15. |
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GH-154648 is a backport of this pull request to the 3.15 branch. |
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… reentrant __index__ (GH-153572) (#154648) gh-153570: Fix use-after-free in bytearray.take_bytes() with a reentrant __index__ (GH-153572) 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__ (GH-91153). (cherry picked from commit ee21d99) Co-authored-by: tonghuaroot (童话) <tonghuaroot@gmail.com>
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Merged and backported to 3.15. Thanks for your fix! |
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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).