Fix DynamicMethodDesc::Destroy vs code heap enumeration race #713
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There is a race between DynamicMethodDesc::Destroy called from the finalizer thread and the MethodDescs enumeration called from ETW::MethodLog::SendEventsForJitMethods at process exit. DynamicMethodDesc::Destroy cleanos up its members m_pSig and m_pszMethodName and then it calls GetLCGMethodResolver()->Destroy(); That calls EEJitManager::FreeCodeMemory, which tries to take the m_CodeHeapCritSec lock. But this lock is already held by the ETW::MethodLog::SendEventsForJitMethods. So the iterator can see half-destroyed DynamicMethodDesc and a crash happens when trying to get the dynamic method name from the m_pszMethodName for the ETW event purposes. The fix is to call the GetLCGMethodResolver()->Destroy() before destroying the m_pSig and m_pszMethodName.
jkotas
approved these changes
Dec 9, 2019
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There is a race between DynamicMethodDesc::Destroy called from
the finalizer thread and the MethodDescs enumeration called from
ETW::MethodLog::SendEventsForJitMethods at process exit.
DynamicMethodDesc::Destroy cleanos up its members m_pSig and
m_pszMethodName and then it calls GetLCGMethodResolver()->Destroy();
That calls EEJitManager::FreeCodeMemory, which tries to take the
m_CodeHeapCritSec lock. But this lock is already held by
the ETW::MethodLog::SendEventsForJitMethods.
So the iterator can see half-destroyed DynamicMethodDesc and
a crash happens when trying to get the dynamic method name
from the m_pszMethodName for the ETW event purposes.
The fix is to call the GetLCGMethodResolver()->Destroy() before
destroying the m_pSig and m_pszMethodName.