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Fix use-after-free bug in registry_watcher #554

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Fix use-after-free bug in registry_watcher #554

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1d0bba8
Fix use-after-free bug in registry_watcher
Oct 28, 2025
4c8cec2
Avoid conflict over m_threadPoolWait access between Release and Relea…
Royar13 Oct 29, 2025
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7 changes: 5 additions & 2 deletions include/wil/registry.h
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Original file line number Diff line number Diff line change
Expand Up @@ -3123,14 +3123,17 @@ namespace details
if (0 == ::InterlockedDecrement(&m_refCount))
{
lock.reset(); // leave the lock before deleting it.
// Make sure callbacks are not running in parallel to destruction.
m_threadPoolWait.reset();
delete this;
}
}

void ReleaseFromCallback(bool rearm)
{
auto lock = m_lock.lock_exclusive();
if (0 == ::InterlockedDecrement(&m_refCount))
auto refCount = ::InterlockedDecrement(&m_refCount);
if (0 == refCount)
{
// Destroy the thread pool wait now to avoid the wait that would occur in the
// destructor. That wait would cause a deadlock since we are doing this from the callback.
Expand All @@ -3139,7 +3142,7 @@ namespace details
delete this;
// Sleep(1); // Enable for testing to find use after free bugs.
}
else if (rearm)
else if (rearm && refCount > 0)
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@dunhor dunhor Oct 30, 2025

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This suggests you are guarding against negative values. If you've seen this actually happen, we'd be very interested to learn more since that would suggest there's a mis-match of AddRef and Release.

{
::SetThreadpoolWait(m_threadPoolWait.get(), m_eventHandle.get(), nullptr);
}
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