1 files changed, 12 insertions, 2 deletions

diff --git a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
index 3598debd636..e784c88344d 100644
--- a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
+++ b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
@@ -123,6 +123,7 @@ public:
 
   void shrinkTo(unsigned N) {
     assert(N <= size() && "Invalid shrinkTo request!");
+    assert(!AnyFwdRefs && "Unexpected forward refs");
     MetadataPtrs.resize(N);
   }
 
@@ -130,6 +131,7 @@ public:
   MDNode *getMDNodeFwdRefOrNull(unsigned Idx);
   void assignValue(Metadata *MD, unsigned Idx);
   void tryToResolveCycles();
+  bool hasFwdRefs() const { return AnyFwdRefs; }
 };
 
 class BitcodeReader : public GVMaterializer {
@@ -1929,6 +1931,9 @@ std::error_code BitcodeReader::parseMetadata(bool ModuleLevel) {
   IsMetadataMaterialized = true;
   unsigned NextMetadataNo = MetadataList.size();
 
+  if (!ModuleLevel && MetadataList.hasFwdRefs())
+    return error("Invalid metadata: fwd refs into function blocks");
+
   if (Stream.EnterSubBlock(bitc::METADATA_BLOCK_ID))
     return error("Invalid record");
 
@@ -3968,6 +3973,10 @@ std::error_code BitcodeReader::parseFunctionBody(Function *F) {
   if (Stream.EnterSubBlock(bitc::FUNCTION_BLOCK_ID))
     return error("Invalid record");
 
+  // Unexpected unresolved metadata when parsing function.
+  if (MetadataList.hasFwdRefs())
+    return error("Invalid function metadata: incoming forward references");
+
   InstructionList.clear();
   unsigned ModuleValueListSize = ValueList.size();
   unsigned ModuleMetadataListSize = MetadataList.size();
@@ -5227,8 +5236,9 @@ OutOfRecordLoop:
     }
   }
 
-  // FIXME: Check for unresolved forward-declared metadata references
-  // and clean up leaks.
+  // Unexpected unresolved metadata about to be dropped.
+  if (MetadataList.hasFwdRefs())
+    return error("Invalid function metadata: outgoing forward refs");
 
   // Trim the value list down to the size it was before we parsed this function.
   ValueList.shrinkTo(ModuleValueListSize);