gh-112887: Fix tarfile FilterError handling to skip member extraction #112954
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In `tarfile` library, FilterError with error_level set to 0 correctly logged a debugging message but did not properly skip extraction of a member. Updates filter functions to return None when a FilterError is seen, as stated in docs.
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Thank you for the fix. I included it, in a “Ship of Theseus” style, in #135037 which fixes a few other security issues as well. I forgot to include you in the Git authorship metadata. I apologize for that. You're credited in What's New though: https://docs.python.org/3.14/whatsnew/3.14.html#tarfile |
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In
tarfilelibrary, if a FilterError is raised for a member duringTarFile.extract()orTarFile.extractall()witherrorlevelset to 0, a debugging message is correctly logged but the unsafe member is still extracted. Based on the documentation and a look at the code, it seems that the desired expectation witherrorlevel=0is to not raise an exception, but skip member extraction and log the error.Updates
tarfileto properly handleFilterErrorand skip extraction on unsafe members even when an exception is not raised.This issue was reported on Python 3.11 and should likely be backported as it is a security issue.
From the docs: