[release/5.0] Remove the sealed blittable layoutclass correctness fix because of backcompat. #54244
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… because of backcompat.
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@jkoritzinsky looks like part of the ci failure is related to the discussion here: dotnet/sdk#18292. Please resolve the other issues and get a cr. |
jeffschwMSFT
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The test failures are #11063 |
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Port of #54235
Customer Impact
Copying data for a non-sealed blittable layout class instead of pinning leads to a use-after-free bug of code on the native heap in NAudio on .NET 5.0.7.
NAudio pins the layoutclass object in managed code and uses the same memory address across multiple native calls. When the fix in #50882 changed the layoutclass marshaller to have some extra safety and not pass non-sealed blittable layout classes by pinning and instead allocate memory and copy, the assumption NAudio made around the object's native representation's address being constant while the managed object is pinned with a pinned GC handle became untrue.
Testing
Testing added in PR.
Fix validated by users.
Risk
Low. This puts our behavior fully 100% in line with 3.1 for our layout class marshalling with no observable differences in behavior for any scenario we know about. I know I said the same thing in #50882, but at the time I did not realize that there was a mechanism to become dependent on the pinning optimization occurring outside of the data marshalling around the call (which #50882 included compat behavior to preserve).
Regression
This is a regression introduced in #50882