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

[Peter Collingbourne via llvm-branch-commits]

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@@ -2201,6 +2215,22 @@ void CodeGenFunction::EmitCXXConstructorCall(
     EmitTypeCheck(CodeGenFunction::TCK_ConstructorCall, Loc, This,
                   getContext().getRecordType(ClassDecl), CharUnits::Zero());
 
+  // When initializing an object that has pointer field protection and whose
+  // fields are not trivially relocatable we must initialize any pointer fields
+  // to a valid signed pointer (any pointer value will do, but we just use null
+  // pointers). This is because if the object is subsequently copied, its copy
+  // constructor will need to read and authenticate any pointer fields in order
+  // to copy the object to a new address, which will fail if the pointers are
+  // uninitialized.
+  if (!getContext().arePFPFieldsTriviallyRelocatable(D->getParent())) {
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pcc wrote:

That's fair. This code was added while testing in our internal codebase at a time when we had a more expansive view of which fields would be subject to PFP. I will re-evaluate whether this is still needed.

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