[release/7.0] Fix edit and continue in VS with hardware exceptions #76427
Conversation
This file contains hidden or 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
![github-actions[bot]](https://avatars.githubusercontent.com/in/15368?s=60&v=4){kind=small}
There is a subtle bug in hardware exception handling in the runtime that causes the debugged process to crash when a user tries to use the "unwind to this frame" on the frame where the exception happened. This issue was introduced by the recent changes that modified hardware exception handling. The problem turned out to be in how we update the exception and context records in the HandleManagedFaultFilter when we re-raise the exception using RaiseException from the VEH. Updating the context is both not necessary and wrong. All we need to update is the `ExceptionAddress` in the `EXCEPTION_RECORD`, since the RaiseException puts the address of itself there and we need the address of the original access violation to be there. The context should stay untouched as we are unwinding from the RaiseException. The context copying was originally made to mimick the code in the `NakedThrowHelper` used before the exception handling change. That one needed the context update, as it was used to fix unwinding over the NakedThrowHelper that was a hijack helper. In the current state, nothing like that is needed. With this fix, the VS debugger works as expected.
ghost
added
the
janvorli
added
os-windows
arch-x64
Servicing-consider
jkotas
approved these changes
Sep 30, 2022
It may be a good idea to ask Visual Studio to run their test suite on this fix. |
Nit: I would not characterize the risk as very low. The test coverage for these areas is not great and this is not the first regression we are fixing after the recent hardware exception handling changes. |
jeffschwMSFT
approved these changes
Sep 30, 2022
tommcdon
approved these changes
Sep 30, 2022
hoyosjs
approved these changes
Sep 30, 2022
jeffschwMSFT
added
Servicing-approved
|
Approved, signed off, CI green. |
Sign up for free
to subscribe to this conversation on GitHub.
Already have an account?
Sign in.
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.
Backport of #76401 to release/7.0
/cc @janvorli
Customer Impact
Without this fix, using the "unwind to this frame" functionality in Visual Studio after a hardware exception like null reference causes the debugged process to crash.
Testing
Local testing with Visual Studio, monitoring the state of the target process using non-invasively attached WinDbg at the same time and comparing the behavior with .NET 6.
Risk
Very low, it touches only the hardware exception handling path and influences only the debugger behavior.