perly LSTOPSUB: prevent a double op free between parse stack and CV #22134
Conversation
This file contains 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
The reeproducer resulted in the "block" OP being both on the parser stack and attacked to the CV. If an error occurred while parsing the rest of the list operator clean up would release the OP as attached to the CV, and the same OP on the parse stack, resulting in a double free. It's unclear to me whether bison is intended to support modifying the parse stack entry like this, but it appears to work here. Fixes Perl#21724
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
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Outdated suggestions cannot be applied.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.
The reproducer resulted in the "block" OP being both on the parser stack and attacked to the CV. If an error occurred while parsing the rest of the list operator clean up would release the OP as attached to the CV, and the same OP on the parse stack, resulting in a double free.
It's unclear to me whether bison is intended to support modifying the parse stack entry like this, but it appears to work here.
Fixes #21724