release/19.x: [ORC] Remove EDU from dependants list of dependencies before destroying. #109355
Conversation
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Hi, since we are wrapping up this next release we are very strict with the fixes we pick at this point. Can you please respond to the following questions to help me understand if this has to be included in the final release or not. Is this PR a fix for a regression or a critical issue? What is the risk of accepting this into the release branch? What is the risk of NOT accepting this into the release branch? |
Sure thing @tru!
This is a fix for a critical issue affecting some JIT users who make use of ORC's concurrent compilation support.
This fix affects only JIT users who use ORC's concurrent compilation support.
JIT users who use concurrent compilation may see crashes in both their JIT process: Failure to remove EDUs from their dependants lists may result in a use-after-free. |
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Sounds like it would be safe enough. I will merge it thanks for responding! |
Dependant lists hold raw pointers back to EDUs that depend on them. We need to remove these entries before destroying the EDU or we'll be left with a dangling reference that can result in use-after-free bugs. No testcase: This has only been observed in multi-threaded setups that reproduce the issue inconsistently. rdar://135403614 (cherry picked from commit 7034ec4)
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@lhames (or anyone else). If you would like to add a note about this fix in the release notes (completely optional). Please reply to this comment with a one or two sentence description of the fix. When you are done, please add the release:note label to this PR. |
Backport 7034ec4
Requested by: @lhames