[PATCH] D142277: [clang][Interp] Clear metadata when destroying locals

[Aaron Ballman via Phabricator via cfe-commits]

aaron.ballman added inline comments.


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Comment at: clang/lib/AST/Interp/EvalEmitter.cpp:260-261
+    // local variable is used after being destroyed.
+    InlineDescriptor &ID = *reinterpret_cast<InlineDescriptor *>(B->rawData());
+    std::memset(&ID, 0, sizeof(InlineDescriptor));
   }
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I'm not certain this is a good idea -- we've just deallocated `B` and then we're saying "cool, now get me your raw data so I can muck about with it".

The comments in `InterpState::deallocate()` say `// Free storage, if necessary.`, so this looks a lot like a use-after-free. Am I missing something?


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Comment at: clang/lib/AST/Interp/InterpFrame.cpp:80-81
+    // local variable is used after being destroyed.
+    InlineDescriptor *ID = localInlineDesc(Local.Offset);
+    std::memset(ID, 0, sizeof(InlineDescriptor));
   }
----------------
Same here as above.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D142277/new/

https://reviews.llvm.org/D142277