[release/9.0] Fix memory corruption bug in virtual static method dispatch - #107776
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- Use `TypeHandle::CanCastTo` instead of `MethodTable::CanCastTo` - The issue is that the `MethodTable` api requires cooperative mode, and the `TypeHandle` supports either mode Fixes #107754
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approved. we can merge when ready
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Backport of #107763 to release/9.0
/cc @davidwrighton
Customer Impact
This bug impacts customers who use the static virtual method feature in combination with interface variance. The only known repro today also requires default interface implementations. The failure mode for customers is memory corruption caused by access to the GC heap which is not synchronized with the GC. This was found when adjusting the runtime in .NET 10 to use a slightly different code path which exposed the bug in many more situations.
Regression
[If yes, specify when the regression was introduced. Provide the PR or commit if known.]
Testing
Newly written regression test, PR testing.
Risk
Low. The change calls a function which is already called in similar situations, and which is capable of doing the correct synchronization with the GC.
IMPORTANT: If this backport is for a servicing release, please verify that:
The PR target branch is
release/X.0-staging, notrelease/X.0.If the change touches code that ships in a NuGet package, you have added the necessary package authoring and gotten it explicitly reviewed.