Fix some fragile code that is likely to cause future memory corruption

problems.

- The ordering of keys in stl containers cannot change. Make the relevant
members const to guarantee this assumption.
- Add handling and logging for demangle errors.
- Fix a potential double-delete bug if a function passed to AddFunction() is
already present.

BUG=chromium:449214
R=mark@chromium.org

Review URL: https://breakpad.appspot.com/10704002/


git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@1415 4c0a9323-5329-0410-9bdc-e9ce6186880e

src/common/dwarf_cu_to_module.cc

@@ -351,9 +351,15 @@ void DwarfCUToModule::GenericDIEHandler::ProcessAttributeString(
       break;
     case dwarf2reader::DW_AT_MIPS_linkage_name: {
       char* demangled = NULL;
+      int status = -1;
 #if !defined(__ANDROID__)
-      demangled = abi::__cxa_demangle(data.c_str(), NULL, NULL, NULL);
+      demangled = abi::__cxa_demangle(data.c_str(), NULL, NULL, &status);
 #endif
+      if (status != 0) {
+        cu_context_->reporter->DemangleError(data, status);
+        demangled_name_ = "";
+        break;
+      }
       if (demangled) {
         demangled_name_ = AddStringToPool(demangled);
         free(reinterpret_cast<void*>(demangled));
@@ -534,18 +540,19 @@ void DwarfCUToModule::FuncHandler::Finish() {
   // functions that were never used), but all the ones we're
   // interested in cover a non-empty range of bytes.
   if (low_pc_ < high_pc_) {
-    // Create a Module::Function based on the data we've gathered, and
-    // add it to the functions_ list.
-    scoped_ptr<Module::Function> func(new Module::Function);
     // Malformed DWARF may omit the name, but all Module::Functions must
     // have names.
+    string name;
     if (!name_.empty()) {
-      func->name = name_;
+      name = name_;
     } else {
       cu_context_->reporter->UnnamedFunction(offset_);
-      func->name = "<name omitted>";
+      name = "<name omitted>";
     }
-    func->address = low_pc_;
+
+    // Create a Module::Function based on the data we've gathered, and
+    // add it to the functions_ list.
+    scoped_ptr<Module::Function> func(new Module::Function(name, low_pc_));
     func->size = high_pc_ - low_pc_;
     func->parameter_size = 0;
     if (func->address) {
@@ -667,6 +674,13 @@ void DwarfCUToModule::WarningReporter::UnnamedFunction(uint64 offset) {
           filename_.c_str(), offset);
 }
 
+void DwarfCUToModule::WarningReporter::DemangleError(
+    const string &input, int error) {
+  CUHeading();
+  fprintf(stderr, "%s: warning: failed to demangle %s with error %d\n",
+          filename_.c_str(), input.c_str(), error);
+}
+
 void DwarfCUToModule::WarningReporter::UnhandledInterCUReference(
     uint64 offset, uint64 target) {
   CUHeading();

src/common/dwarf_cu_to_module.h

@@ -199,6 +199,9 @@ class DwarfCUToModule: public dwarf2reader::RootDIEHandler {
     // link.
     virtual void UnnamedFunction(uint64 offset);
 
+    // __cxa_demangle() failed to demangle INPUT.
+    virtual void DemangleError(const string &input, int error);
+
     // The DW_FORM_ref_addr at OFFSET to TARGET was not handled because
     // FilePrivate did not retain the inter-CU specification data.
     virtual void UnhandledInterCUReference(uint64 offset, uint64 target);

src/common/dwarf_cu_to_module_unittest.cc

@@ -81,6 +81,7 @@ class MockWarningReporter: public DwarfCUToModule::WarningReporter {
   MOCK_METHOD1(UncoveredFunction, void(const Module::Function &function));
   MOCK_METHOD1(UncoveredLine, void(const Module::Line &line));
   MOCK_METHOD1(UnnamedFunction, void(uint64 offset));
+  MOCK_METHOD2(DemangleError, void(const string &input, int error));
   MOCK_METHOD2(UnhandledInterCUReference, void(uint64 offset, uint64 target));
 };
 
@@ -1712,16 +1713,14 @@ TEST_F(CUErrors, BadCURootDIETag) {
 // produce) output, so their results need to be checked by hand.
 struct Reporter: public Test {
   Reporter()
-      : reporter("filename", 0x123456789abcdef0ULL) {
+      : reporter("filename", 0x123456789abcdef0ULL),
+        function("function name", 0x19c45c30770c1eb0ULL),
+        file("source file name") {
     reporter.SetCUName("compilation-unit-name");
 
-    function.name = "function name";
-    function.address = 0x19c45c30770c1eb0ULL;
     function.size = 0x89808a5bdfa0a6a3ULL;
     function.parameter_size = 0x6a329f18683dcd51ULL;
 
-    file.name = "source file name";
-
     line.address = 0x3606ac6267aebeccULL;
     line.size = 0x5de482229f32556aULL;
     line.file = &file;

src/common/linux/elf_symbols_to_module.cc

@@ -155,9 +155,8 @@ bool ELFSymbolsToModule(const uint8_t *symtab_section,
   while(!iterator->at_end) {
     if (ELF32_ST_TYPE(iterator->info) == STT_FUNC &&
         iterator->shndx != SHN_UNDEF) {
-      Module::Extern *ext = new Module::Extern;
+      Module::Extern *ext = new Module::Extern(iterator->value);
       ext->name = SymbolString(iterator->name_offset, strings);
-      ext->address = iterator->value;
       module->AddExtern(ext);
     }
     ++iterator;

src/common/module.cc

@@ -80,7 +80,7 @@ void Module::AddFunction(Function *function) {
   // callers try to add one.
   assert(!function->name.empty());
   std::pair<FunctionSet::iterator,bool> ret = functions_.insert(function);
-  if (!ret.second) {
+  if (!ret.second && (*ret.first != function)) {
     // Free the duplicate that was not inserted because this Module
     // now owns it.
     delete function;
@@ -98,9 +98,7 @@ void Module::AddStackFrameEntry(StackFrameEntry *stack_frame_entry) {
 }
 
 void Module::AddExtern(Extern *ext) {
-  Function func;
-  func.name = ext->name;
-  func.address = ext->address;
+  Function func(ext->name, ext->address);
 
   // Since parsing debug section and public info are not necessarily
   // mutually exclusive, check if the symbol has already been read
@@ -141,8 +139,7 @@ Module::File *Module::FindFile(const string &name) {
   FileByNameMap::iterator destiny = files_.lower_bound(&name);
   if (destiny == files_.end()
       || *destiny->first != name) {  // Repeated string comparison, boo hoo.
-    File *file = new File;
-    file->name = name;
+    File *file = new File(name);
     file->source_id = -1;
     destiny = files_.insert(destiny,
                             FileByNameMap::value_type(&file->name, file));

src/common/module.h

@@ -74,8 +74,10 @@ class Module {
 
   // A source file.
   struct File {
+    explicit File(const string &name_input) : name(name_input), source_id(0) {}
+
     // The name of the source file.
-    string name;
+    const string name;
 
     // The file's source id.  The Write member function clears this
     // field and assigns source ids a fresh, so any value placed here
@@ -85,6 +87,9 @@ class Module {
 
   // A function.
   struct Function {
+    Function(const string &name_input, const Address &address_input) :
+        name(name_input), address(address_input), size(0), parameter_size(0) {}
+
     // For sorting by address.  (Not style-guide compliant, but it's
     // stupid not to put this in the struct.)
     static bool CompareByAddress(const Function *x, const Function *y) {
@@ -92,10 +97,11 @@ class Module {
     }
 
     // The function's name.
-    string name;
+    const string name;
 
     // The start address and length of the function's code.
-    Address address, size;
+    const Address address;
+    Address size;
 
     // The function's parameter size.
     Address parameter_size;
@@ -120,7 +126,8 @@ class Module {
 
   // An exported symbol.
   struct Extern {
-    Address address;
+    explicit Extern(const Address &address_input) : address(address_input) {}
+    const Address address;
     string name;
   };
 

src/common/module_unittest.cc

@@ -54,9 +54,7 @@ static Module::Function *generate_duplicate_function(const string &name) {
   const Module::Address DUP_SIZE = 0x200b26e605f99071LL;
   const Module::Address DUP_PARAMETER_SIZE = 0xf14ac4fed48c4a99LL;
 
-  Module::Function *function = new(Module::Function);
-  function->name = name;
-  function->address = DUP_ADDRESS;
+  Module::Function *function = new Module::Function(name, DUP_ADDRESS);
   function->size = DUP_SIZE;
   function->parameter_size = DUP_PARAMETER_SIZE;
   return function;
@@ -81,9 +79,8 @@ TEST(Write, OneLineFunc) {
   Module m(MODULE_NAME, MODULE_OS, MODULE_ARCH, MODULE_ID);
 
   Module::File *file = m.FindFile("file_name.cc");
-  Module::Function *function = new(Module::Function);
-  function->name = "function_name";
-  function->address = 0xe165bf8023b9d9abLL;
+  Module::Function *function = new Module::Function(
+      "function_name", 0xe165bf8023b9d9abLL);
   function->size = 0x1e4bb0eb1cbf5b09LL;
   function->parameter_size = 0x772beee89114358aLL;
   Module::Line line = { 0xe165bf8023b9d9abLL, 0x1e4bb0eb1cbf5b09LL,
@@ -110,9 +107,8 @@ TEST(Write, RelativeLoadAddress) {
   Module::File *file2 = m.FindFile("filename-a.cc");
 
   // A function.
-  Module::Function *function = new(Module::Function);
-  function->name = "A_FLIBBERTIJIBBET::a_will_o_the_wisp(a clown)";
-  function->address = 0xbec774ea5dd935f3LL;
+  Module::Function *function = new Module::Function(
+      "A_FLIBBERTIJIBBET::a_will_o_the_wisp(a clown)", 0xbec774ea5dd935f3LL);
   function->size = 0x2922088f98d3f6fcLL;
   function->parameter_size = 0xe5e9aa008bd5f0d0LL;
 
@@ -168,9 +164,8 @@ TEST(Write, OmitUnusedFiles) {
   Module::File *file3 = m.FindFile("filename3");
 
   // Create a function.
-  Module::Function *function = new(Module::Function);
-  function->name = "function_name";
-  function->address = 0x9b926d464f0b9384LL;
+  Module::Function *function = new Module::Function(
+      "function_name", 0x9b926d464f0b9384LL);
   function->size = 0x4f524a4ba795e6a6LL;
   function->parameter_size = 0xbbe8133a6641c9b7LL;
 
@@ -217,9 +212,8 @@ TEST(Write, NoCFI) {
   Module::File *file1 = m.FindFile("filename.cc");
 
   // A function.
-  Module::Function *function = new(Module::Function);
-  function->name = "A_FLIBBERTIJIBBET::a_will_o_the_wisp(a clown)";
-  function->address = 0xbec774ea5dd935f3LL;
+  Module::Function *function = new Module::Function(
+      "A_FLIBBERTIJIBBET::a_will_o_the_wisp(a clown)", 0xbec774ea5dd935f3LL);
   function->size = 0x2922088f98d3f6fcLL;
   function->parameter_size = 0xe5e9aa008bd5f0d0LL;
 
@@ -260,15 +254,13 @@ TEST(Construct, AddFunctions) {
   Module m(MODULE_NAME, MODULE_OS, MODULE_ARCH, MODULE_ID);
 
   // Two functions.
-  Module::Function *function1 = new(Module::Function);
-  function1->name = "_without_form";
-  function1->address = 0xd35024aa7ca7da5cLL;
+  Module::Function *function1 = new Module::Function(
+      "_without_form", 0xd35024aa7ca7da5cLL);
   function1->size = 0x200b26e605f99071LL;
   function1->parameter_size = 0xf14ac4fed48c4a99LL;
 
-  Module::Function *function2 = new(Module::Function);
-  function2->name = "_and_void";
-  function2->address = 0x2987743d0b35b13fLL;
+  Module::Function *function2 = new Module::Function(
+      "_and_void", 0x2987743d0b35b13fLL);
   function2->size = 0xb369db048deb3010LL;
   function2->parameter_size = 0x938e556cb5a79988LL;
 
@@ -443,11 +435,9 @@ TEST(Construct, Externs) {
   Module m(MODULE_NAME, MODULE_OS, MODULE_ARCH, MODULE_ID);
 
   // Two externs.
-  Module::Extern *extern1 = new(Module::Extern);
-  extern1->address = 0xffff;
+  Module::Extern *extern1 = new Module::Extern(0xffff);
   extern1->name = "_abc";
-  Module::Extern *extern2 = new(Module::Extern);
-  extern2->address = 0xaaaa;
+  Module::Extern *extern2 = new Module::Extern(0xaaaa);
   extern2->name = "_xyz";
 
   m.AddExtern(extern1);
@@ -470,11 +460,9 @@ TEST(Construct, DuplicateExterns) {
   Module m(MODULE_NAME, MODULE_OS, MODULE_ARCH, MODULE_ID);
 
   // Two externs.
-  Module::Extern *extern1 = new(Module::Extern);
-  extern1->address = 0xffff;
+  Module::Extern *extern1 = new Module::Extern(0xffff);
   extern1->name = "_xyz";
-  Module::Extern *extern2 = new(Module::Extern);
-  extern2->address = 0xffff;
+  Module::Extern *extern2 = new Module::Extern(0xffff);
   extern2->name = "_abc";
 
   m.AddExtern(extern1);

src/common/stabs_to_module.cc

@@ -90,9 +90,7 @@ bool StabsToModule::EndCompilationUnit(uint64_t address) {
 bool StabsToModule::StartFunction(const string &name,
                                   uint64_t address) {
   assert(!current_function_);
-  Module::Function *f = new Module::Function;
-  f->name = Demangle(name);
-  f->address = address;
+  Module::Function *f = new Module::Function(Demangle(name), address);
   f->size = 0;           // We compute this in StabsToModule::Finalize().
   f->parameter_size = 0; // We don't provide this information.
   current_function_ = f;
@@ -133,7 +131,7 @@ bool StabsToModule::Line(uint64_t address, const char *name, int number) {
 }
 
 bool StabsToModule::Extern(const string &name, uint64_t address) {
-  Module::Extern *ext = new Module::Extern;
+  Module::Extern *ext = new Module::Extern(address);
   // Older libstdc++ demangle implementations can crash on unexpected
   // input, so be careful about what gets passed in.
   if (name.compare(0, 3, "__Z") == 0) {
@@ -143,7 +141,6 @@ bool StabsToModule::Extern(const string &name, uint64_t address) {
   } else {
     ext->name = name;
   }
-  ext->address = address;
   module_->AddExtern(ext);
   return true;
 }