gh-148688: Fix _BlocksOutputBuffer_Finish() double free#148689
Open
vstinner wants to merge 3 commits intopython:mainfrom
Open
gh-148688: Fix _BlocksOutputBuffer_Finish() double free#148689vstinner wants to merge 3 commits intopython:mainfrom
vstinner wants to merge 3 commits intopython:mainfrom
Conversation
If _BlocksOutputBuffer_Finish() fails (memory allocation failure), PyBytesWriter_Discard() is called on the writer. Then if _BlocksOutputBuffer_OnError() is called, it calls again PyBytesWriter_Discard() causing a double free. Fix _BlocksOutputBuffer_Finish() by setting buffer->writer to NULL, so _BlocksOutputBuffer_OnError() does nothing instead of calling PyBytesWriter_Discard() again.
vstinner
added
needs backport to 3.14
emmatyping
approved these changes
Apr 17, 2026
Member
|
You may want to also list compression.zstd, since it also uses BlocksOutputBuffer |
Member
Author
Ah yes! I updated the NEWS entry. Thanks for the review! |
serhiy-storchaka
approved these changes
Apr 18, 2026
| @@ -0,0 +1,2 @@ | |||
| :mod:`bz2`, :mod:`compression.zstd`, :mod:`lzma`, :mod:`zlib`: Fix a double | |||
| free in on memory allocation failure. Patch by Victor Stinner. | |||
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
3 participants
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
If _BlocksOutputBuffer_Finish() fails (memory allocation failure), PyBytesWriter_Discard() is called on the writer. Then if _BlocksOutputBuffer_OnError() is called, it calls again PyBytesWriter_Discard() causing a double free.
Fix _BlocksOutputBuffer_Finish() by setting buffer->writer to NULL, so _BlocksOutputBuffer_OnError() does nothing instead of calling PyBytesWriter_Discard() again.