[llvm-branch-commits] Add pointer field protection feature. (PR #133538)

[Oliver Hunt via llvm-branch-commits]

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@@ -7538,6 +7538,14 @@ static bool IsEligibleForTrivialRelocation(Sema &SemaRef,
     if (!SemaRef.IsCXXTriviallyRelocatableType(Field->getType()))
       return false;
   }
+
+  // FIXME: PFP should not affect trivial relocatability, instead it should
+  // affect the implementation of std::trivially_relocate. See:
+  // https://discourse.llvm.org/t/rfc-structure-protection-a-family-of-uaf-mitigation-techniques/85555/16?u=pcc
+  if (!SemaRef.Context.arePFPFieldsTriviallyRelocatable(D) &&
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ojhunt wrote:

If PFP fields are present, and we haven't yet implemented support for them in `trivially_relocate`, `IsCXXTriviallyRelocatableType` should be returning false.

This is something we have to address for address discriminated pointer auth as well.

https://github.com/llvm/llvm-project/pull/133538