[release/9.0-staging] Fix race condition in cleanup of collectible thread static variables #111275
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There was a race condition where we could have collected all of the managed state of a LoaderAllocator, but not yet started cleaning up the actual LoaderAllocator object in native code. If a thread which had a TLS variable defined in a code associated with a collectible loader allocator was terminated at that point, then the runtime would crash. The fix is to detect if the LoaderAllocator managed state is still alive, and if so, do not attempt to clean it up.
…taticCollection.cs Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
…taticCollection.cs Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
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@davidwrighton @jeffschwMSFT friendly reminder that today's code complete for the Feb 2025 Release. Please merge this change by 4pm PT if you'd like it included in that release version. Otherwise, it will have to wait until next month. |
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Backport of #111257 to release/9.0-staging
/cc @davidwrighton
Customer Impact
This race condition causes an access violation in the EE accessing null when a collectible assembly is partially collected and a thread is terminated. And that thread used a collectible tls static. Found by dnceng in a CI environment.
Regression
This was introduced with the statics rewrite.
Testing
New stress test was written to verify the fix. A cut down variant of the stress test has been added as part of the fix.
Risk
Low , fix is effectively a null check that just skips doing the problematic operation.
IMPORTANT: If this backport is for a servicing release, please verify that:
release/X.0-staging, notrelease/X.0.Package authoring no longer needed in .NET 9
IMPORTANT: Starting with .NET 9, you no longer need to edit a NuGet package's csproj to enable building and bump the version.
Keep in mind that we still need package authoring in .NET 8 and older versions.