llvm-undname: Fix nullptr deref on invalid structor names in template args

Similar to r358421: A StructorIndentifierNode has a Class field which
is read when printing it, but if the StructorIndentifierNode appears in
a template argument then demangleFullyQualifiedSymbolName() which sets
Class isn't called. Since StructorIndentifierNodes are always leaf
names, we can just reject them as well.

Found by oss-fuzz.

llvm-svn: 358491

1 files changed, 4 insertions, 3 deletions

diff --git a/llvm/lib/Demangle/MicrosoftDemangle.cpp b/llvm/lib/Demangle/MicrosoftDemangle.cpp
index c3bdfa23d1f..49cfcde9c58 100644
--- a/llvm/lib/Demangle/MicrosoftDemangle.cpp
+++ b/llvm/lib/Demangle/MicrosoftDemangle.cpp
@@ -949,9 +949,10 @@ Demangler::demangleTemplateInstantiationName(StringView &MangledName,
 
   if (NBB & NBB_Template) {
     // NBB_Template is only set for types and non-leaf names ("a::" in "a::b").
-    // A conversion operator only makes sense in a leaf name , so reject it in
-    // NBB_Template contexts.
-    if (Identifier->kind() == NodeKind::ConversionOperatorIdentifier) {
+    // Structors and conversion operators only makes sense in a leaf name, so
+    // reject them in NBB_Template contexts.
+    if (Identifier->kind() == NodeKind::ConversionOperatorIdentifier ||
+        Identifier->kind() == NodeKind::StructorIdentifier) {
       Error = true;
       return nullptr;
     }