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Bug 1838286 - Fix a race condition with in-process DLL interception. r=win-reviewers,gstoll

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If a thread starts running a detoured function right after we
successfully committed our 13-bytes patch, there is a short delay where
it can reach the patched_XXX function and try to call stub_XXX while
stub_XXX.mOrigFunc is still a null pointer.

We fix this specific race condition, which, in the current code base,
materializes mostly as crashes in patched_BaseThreadInitThunk when
trying to call stub_BaseThreadInitThunk.

Differential Revision: https://phabricator.services.mozilla.com/D192668
This commit is contained in:
Yannis Juglaret 2023-11-03 16:57:50 +00:00
parent 9529ca9444
commit a5fe9e5af0
1 changed files with 7 additions and 5 deletions
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12
toolkit/xre/dllservices/mozglue/interceptor/PatcherDetour.h
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@ -1737,12 +1737,14 @@ class WindowsDllDetourPatcher final
PrimitiveT::ApplyDefaultPatch(target, aDest);
} while (false);
if (!target.Commit()) {
return;
}
// Output the trampoline, thus signalling that this call was a success
// Output the trampoline, thus signalling that this call was a success. This
// must happen before our patched function can be reached from another
// thread, so before we commit the target code (bug 1838286).
*aOutTramp = trampPtr;
if (!target.Commit()) {
*aOutTramp = nullptr;
}
}
};