Fix a use after free on invalid input.

llvm-svn: 193737

llvm/lib/Bitcode/Reader/BitcodeReader.cpp

@@ -623,11 +623,7 @@ bool BitcodeReader::ParseAttrKind(uint64_t Code, Attribute::AttrKind *Kind) {
     *Kind = Attribute::ZExt;
     return false;
   default:
-    std::string Buf;
+    return Error("Unknown attribute kind");
-    raw_string_ostream fmt(Buf);
-    fmt << "Unknown attribute kind (" << Code << ")";
-    fmt.flush();
-    return Error(Buf.c_str());
   }
 }
 

llvm/test/Bitcode/invalid.ll

@@ -0,0 +1,7 @@
+; RUN:  not llvm-dis < %s.bc 2>&1 | FileCheck %s
+
+; CHECK: llvm-dis: Unknown attribute kind
+
+; invalid.ll.bc has an invalid attribute number.
+; The test checks that LLVM reports the error and doesn't access freed memory
+; in doing so.