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Add null check for ThreadLocalStoragePointer in COMUnhandledExceptionFilter to prevent crash on Windows #123826

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Merged
jkotas merged 6 commits into from
Feb 2, 2026
Merged

Add null check for ThreadLocalStoragePointer in COMUnhandledExceptionFilter to prevent crash on Windows #123826

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ea81c31
Initial plan
Copilot Jan 31, 2026
890dfa3
Add exception handler to protect against access violations in COMUnha…
Copilot Jan 31, 2026
0ef7da5
Protect GetThreadNULLOk() call with exception handler in COMUnhandled…
Copilot Jan 31, 2026
71288f5
Add null check for ThreadLocalStoragePointer in COMUnhandledException…
Copilot Jan 31, 2026
8a70d87
Update src/coreclr/vm/excep.cpp
jkotas Jan 31, 2026
31647cb
Wrap NtCurrentTeb check with TARGET_WINDOWS ifdef to fix Unix build
Copilot Jan 31, 2026
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8 changes: 8 additions & 0 deletions src/coreclr/vm/excep.cpp
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Expand Up @@ -4312,6 +4312,14 @@ LONG __stdcall COMUnhandledExceptionFilter( // EXCEPTION_CONTINUE_SEARCH or

LONG retVal = EXCEPTION_CONTINUE_SEARCH;

#ifdef TARGET_WINDOWS
if (NtCurrentTeb()->ThreadLocalStoragePointer == NULL)
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{
// Early out when TLS is not available due to unhandled exception during early thread initialization
return retVal;
}
#endif // TARGET_WINDOWS

// Incase of unhandled exceptions on managed threads, we kick in our UE processing at the thread base and also invoke
// UEF callbacks that various runtimes have registered with us. Once the callbacks return, we return back to the OS
// to give other registered UEFs a chance to do their custom processing.
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