[lldb][Language] Pass SymbolNameFitsToLanguage parameter by const-ref

[Michael137]

We've been seeing (rare) crashes from both CPlusPlusLanguage::SymbolNameFitsToLanguage and ObjCLanguage::SymbolNameFitsToLanguage when we try to read contents of the ConstStrings of the Mangled parameter. I'm not entirely sure how that can happen (current theory is corrupted stack somehow which overwrites ConstString::m_string to an invalid pointer) but I'm not able to confirm that.

One thing these crashes had in common is that they operate on the Mangled object we copied into SymbolNameFitsToLanguage by value. While I can't see off the top why that would cause it to contain unintiailized/corrupt ConstStrings, the class is sufficiently large enough to probably pass it by const & anyway. This is what this patch does.

rdar://164519648

[llvmbot]

@llvm/pr-subscribers-lldb

Author: Michael Buch (Michael137)

Changes

We've been seeing (rare) crashes from both CPlusPlusLanguage::SymbolNameFitsToLanguage and ObjCLanguage::SymbolNameFitsToLanguage when we try to read contents of the ConstStrings of the Mangled parameter. I'm not entirely sure how that can happen (current theory is corrupted stack somehow which overwrites ConstString::m_string to an invalid pointer) but I'm not able to confirm that.

One thing these crashes had in common is that they operate on the Mangled object we copied into SymbolNameFitsToLanguage by value. While I can't see off the top why that would cause it to contain unintiailized/corrupt ConstStrings, the class is sufficiently large enough to probably pass it by const & anyway. This is what this patch does.

rdar://164519648

---

Full diff: https://github.com/llvm/llvm-project/pull/167684.diff

5 Files Affected:

• (modified) lldb/include/lldb/Target/Language.h (+3-1)
• (modified) lldb/source/Plugins/Language/CPlusPlus/CPlusPlusLanguage.cpp (+1-1)
• (modified) lldb/source/Plugins/Language/CPlusPlus/CPlusPlusLanguage.h (+1-1)
• (modified) lldb/source/Plugins/Language/ObjC/ObjCLanguage.cpp (+1-1)
• (modified) lldb/source/Plugins/Language/ObjC/ObjCLanguage.h (+1-1)

diff --git a/lldb/include/lldb/Target/Language.h b/lldb/include/lldb/Target/Language.h
index 9958b6ea2f815..9292f790333a1 100644
--- a/lldb/include/lldb/Target/Language.h
+++ b/lldb/include/lldb/Target/Language.h
@@ -318,7 +318,9 @@ class Language : public PluginInterface {
   ///
   /// This function should only return true if there is a high confidence
   /// that the name actually belongs to this language.
-  virtual bool SymbolNameFitsToLanguage(Mangled name) const { return false; }
+  virtual bool SymbolNameFitsToLanguage(const Mangled &name) const {
+    return false;
+  }
 
   /// An individual data formatter may apply to several types and cross language
   /// boundaries. Each of those languages may want to customize the display of
diff --git a/lldb/source/Plugins/Language/CPlusPlus/CPlusPlusLanguage.cpp b/lldb/source/Plugins/Language/CPlusPlus/CPlusPlusLanguage.cpp
index a2199cb65cd35..e935ea8fab813 100644
--- a/lldb/source/Plugins/Language/CPlusPlus/CPlusPlusLanguage.cpp
+++ b/lldb/source/Plugins/Language/CPlusPlus/CPlusPlusLanguage.cpp
@@ -103,7 +103,7 @@ CPlusPlusLanguage::GetFunctionNameInfo(ConstString name) const {
     return {func_name_type, ConstString(basename)};
 }
 
-bool CPlusPlusLanguage::SymbolNameFitsToLanguage(Mangled mangled) const {
+bool CPlusPlusLanguage::SymbolNameFitsToLanguage(const Mangled &mangled) const {
   auto mangling_scheme =
       Mangled::GetManglingScheme(mangled.GetMangledName().GetStringRef());
   return mangling_scheme == Mangled::eManglingSchemeItanium ||
diff --git a/lldb/source/Plugins/Language/CPlusPlus/CPlusPlusLanguage.h b/lldb/source/Plugins/Language/CPlusPlus/CPlusPlusLanguage.h
index 9a528ca7b03f9..13d436a68c691 100644
--- a/lldb/source/Plugins/Language/CPlusPlus/CPlusPlusLanguage.h
+++ b/lldb/source/Plugins/Language/CPlusPlus/CPlusPlusLanguage.h
@@ -92,7 +92,7 @@ class CPlusPlusLanguage : public Language {
 
   static llvm::StringRef GetPluginNameStatic() { return "cplusplus"; }
 
-  bool SymbolNameFitsToLanguage(Mangled mangled) const override;
+  bool SymbolNameFitsToLanguage(const Mangled &mangled) const override;
 
   bool DemangledNameContainsPath(llvm::StringRef path,
                                  ConstString demangled) const override;
diff --git a/lldb/source/Plugins/Language/ObjC/ObjCLanguage.cpp b/lldb/source/Plugins/Language/ObjC/ObjCLanguage.cpp
index 3b8e21cbb9269..5e31faccb315c 100644
--- a/lldb/source/Plugins/Language/ObjC/ObjCLanguage.cpp
+++ b/lldb/source/Plugins/Language/ObjC/ObjCLanguage.cpp
@@ -235,7 +235,7 @@ ObjCLanguage::GetFunctionNameInfo(ConstString name) const {
   return {func_name_type, std::nullopt};
 }
 
-bool ObjCLanguage::SymbolNameFitsToLanguage(Mangled mangled) const {
+bool ObjCLanguage::SymbolNameFitsToLanguage(const Mangled &mangled) const {
   ConstString demangled_name = mangled.GetDemangledName();
   if (!demangled_name)
     return false;
diff --git a/lldb/source/Plugins/Language/ObjC/ObjCLanguage.h b/lldb/source/Plugins/Language/ObjC/ObjCLanguage.h
index a68ea41c723de..729230dc2dccb 100644
--- a/lldb/source/Plugins/Language/ObjC/ObjCLanguage.h
+++ b/lldb/source/Plugins/Language/ObjC/ObjCLanguage.h
@@ -145,7 +145,7 @@ class ObjCLanguage : public Language {
   std::pair<lldb::FunctionNameType, std::optional<ConstString>>
   GetFunctionNameInfo(ConstString name) const override;
 
-  bool SymbolNameFitsToLanguage(Mangled mangled) const override;
+  bool SymbolNameFitsToLanguage(const Mangled &mangled) const override;
 
   lldb::TypeCategoryImplSP GetFormatters() override;
 

[felipepiovezan]

LGTM!