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Fix ComWrappers ICustomQueryInterface exception handling - #132716
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When the user's ICustomQueryInterface.GetInterface implementation throws, the UnmanagedCallersOnly wrapper caught the exception but returned default (0), which is TryInvokeICustomQueryInterfaceResult.Handled. This told native code the call succeeded with *ppvObject set, but it was still null, tripping the QueryInterface assertion in comwrappers.cpp and crashing the process. Return -1 (FailedToInvoke) instead so native code falls back correctly. Fixes the assertion failure in Regressions/coreclr/GitHub_117393/test117393 (#132677). Co-authored-by: Copilot <[email protected]>
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Pull request overview
Fixes incorrect return value from the [UnmanagedCallersOnly] ComWrappers.CallICustomQueryInterface wrapper when ICustomQueryInterface.GetInterface throws, ensuring the native COM QueryInterface path treats the call as failed-to-invoke instead of “handled”.
Changes:
- In the exception path, return
-1(maps toTryInvokeICustomQueryInterfaceResult.FailedToInvoke) instead ofdefault/0(maps toHandled). - Add an inline comment clarifying the intended enum mapping for the
-1return value.
AaronRobinsonMSFT
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Aug 24, 2026
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Should we also backport to .NET 11?
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/backport to release/11.0 |
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Sep 5, 2026
…ng (#132725) Backport of #132716 to release/11.0 /cc @jkoritzinsky ## Customer Impact - [ ] Customer reported - [X] Found internally User gets a null object from a `QueryInterface` against a .NET object that implements `ICustomQueryInterface` exposed to COM via ComWrappers that causes the `ICustomQueryInterface` implementation to throw an exception ## Regression - [X] Yes - [ ] No Regressed in #125697 ## Testing Caught in outerloop testing ## Risk Low. Targeted scenario and we have testing validation. **IMPORTANT**: If this backport is for a servicing release, please verify that: - For .NET 8 and .NET 9: The PR target branch is `release/X.0-staging`, not `release/X.0`. - For .NET 10+: The PR target branch is `release/X.0` (no `-staging` suffix). ## 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. Co-authored-by: Jeremy Koritzinsky <[email protected]> Co-authored-by: Jeremy Koritzinsky <[email protected]> Co-authored-by: Copilot <[email protected]>
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Description
When a user's
ICustomQueryInterface.GetInterfaceimplementation throws an exception, the nativeQueryInterfacepath incomwrappers.cppasserts and crashes the process (Assertion failed: ((*ppvObject != nullptr))).The root cause is in the
[UnmanagedCallersOnly]CallICustomQueryInterfacewrapper inComWrappers.CoreCLR.cs. It catches the exception but returnsdefault(0) from the catch block.0happens to be the numeric value ofTryInvokeICustomQueryInterfaceResult.Handled, so native code is told the call succeeded and that*ppvObjectwas set - but it's stillnull, tripping the assert.The fix returns
-1(TryInvokeICustomQueryInterfaceResult.FailedToInvoke) from the catch block instead, so native code correctly treats the call as failed and falls back rather than asserting on a null pointer.Fixes the CI failure reported in #132677, reproduced locally by
Regressions/coreclr/GitHub_117393/test117393.Verification
clr+libs, builttest117393, generatedCore_Root- test passes with the fix applied.System.Private.CoreLibonly, reran the test - reproduced the exact native assertion crash from the issue.Closes #132677
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This description was generated with AI assistance.