Lock accesses to OptionValueFileSpecList objects

Before a Debugger gets a Target, target settings are routed to a global set
of settings. Even without this, some part of the LLDB which exist independently
of the Debugger object (the Module cache, the Symbol vendors, ...) access
directly the global default store for those settings.

Of course, if you modify one of those global settings while they are being read,
bad things happen. We see this quite a bit with FileSpecList settings. In
particular, we see many cases where one debug session changes
target.exec-search-paths while another session starts up and it crashes when
one of those accesses invalid FileSpecs.

This patch addresses the specific FileSpecList issue by adding locking to
OptionValueFileSpecList and never returning by reference.

Reviewers: clayborg

Subscribers: lldb-commits

Differential Revision: https://reviews.llvm.org/D60468

llvm-svn: 359028

5 files changed, 9 insertions, 8 deletions

diff --git a/lldb/source/Plugins/DynamicLoader/Darwin-Kernel/DynamicLoaderDarwinKernel.cpp b/lldb/source/Plugins/DynamicLoader/Darwin-Kernel/DynamicLoaderDarwinKernel.cpp
index b377c23abb0..ab1cd93e4e3 100644
--- a/lldb/source/Plugins/DynamicLoader/Darwin-Kernel/DynamicLoaderDarwinKernel.cpp
+++ b/lldb/source/Plugins/DynamicLoader/Darwin-Kernel/DynamicLoaderDarwinKernel.cpp
@@ -804,10 +804,11 @@ bool DynamicLoaderDarwinKernel::KextImageInfo::LoadImageUsingMemoryModule(
         if (platform_name == g_platform_name) {
           ModuleSpec kext_bundle_module_spec(module_spec);
           FileSpec kext_filespec(m_name.c_str());
+	  FileSpecList search_paths = target.GetExecutableSearchPaths();
           kext_bundle_module_spec.GetFileSpec() = kext_filespec;
           platform_sp->GetSharedModule(
               kext_bundle_module_spec, process, m_module_sp,
-              &target.GetExecutableSearchPaths(), NULL, NULL);
+              &search_paths, NULL, NULL);
         }
       }
 
diff --git a/lldb/source/Plugins/ExpressionParser/Clang/ClangModulesDeclVendor.cpp b/lldb/source/Plugins/ExpressionParser/Clang/ClangModulesDeclVendor.cpp
index 993843fd721..941306fc0c3 100644
--- a/lldb/source/Plugins/ExpressionParser/Clang/ClangModulesDeclVendor.cpp
+++ b/lldb/source/Plugins/ExpressionParser/Clang/ClangModulesDeclVendor.cpp
@@ -608,7 +608,7 @@ ClangModulesDeclVendor::Create(Target &target) {
     compiler_invocation_arguments.push_back(module_cache_argument);
   }
 
-  FileSpecList &module_search_paths = target.GetClangModuleSearchPaths();
+  FileSpecList module_search_paths = target.GetClangModuleSearchPaths();
 
   for (size_t spi = 0, spe = module_search_paths.GetSize(); spi < spe; ++spi) {
     const FileSpec &search_path = module_search_paths.GetFileSpecAtIndex(spi);
diff --git a/lldb/source/Plugins/Platform/MacOSX/PlatformDarwinKernel.cpp b/lldb/source/Plugins/Platform/MacOSX/PlatformDarwinKernel.cpp
index f67ddda786e..cb453b529d9 100644
--- a/lldb/source/Plugins/Platform/MacOSX/PlatformDarwinKernel.cpp
+++ b/lldb/source/Plugins/Platform/MacOSX/PlatformDarwinKernel.cpp
@@ -208,9 +208,9 @@ public:
         NULL, idx, g_properties[idx].default_uint_value != 0);
   }
 
-  FileSpecList &GetKextDirectories() const {
+  FileSpecList GetKextDirectories() const {
     const uint32_t idx = ePropertyKextDirectories;
-    OptionValueFileSpecList *option_value =
+    const OptionValueFileSpecList *option_value =
         m_collection_sp->GetPropertyAtIndexAsOptionValueFileSpecList(
             NULL, false, idx);
     assert(option_value);
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
index f9b3143cb78..b9ad32c15b0 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
+++ b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
@@ -136,8 +136,8 @@ public:
     m_collection_sp->Initialize(g_properties);
   }
 
-  FileSpecList &GetSymLinkPaths() {
-    OptionValueFileSpecList *option_value =
+  FileSpecList GetSymLinkPaths() {
+    const OptionValueFileSpecList *option_value =
         m_collection_sp->GetPropertyAtIndexAsOptionValueFileSpecList(
             nullptr, true, ePropertySymLinkPaths);
     assert(option_value);
@@ -159,7 +159,7 @@ static const SymbolFileDWARFPropertiesSP &GetGlobalPluginProperties() {
 
 } // anonymous namespace end
 
-const FileSpecList &SymbolFileDWARF::GetSymlinkPaths() {
+FileSpecList SymbolFileDWARF::GetSymlinkPaths() {
   return GetGlobalPluginProperties()->GetSymLinkPaths();
 }
 
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.h b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.h
index 42ae231248b..21008807767 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.h
+++ b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.h
@@ -80,7 +80,7 @@ public:
   static lldb_private::SymbolFile *
   CreateInstance(lldb_private::ObjectFile *obj_file);
 
-  static const lldb_private::FileSpecList &GetSymlinkPaths();
+  static lldb_private::FileSpecList GetSymlinkPaths();
 
   // Constructors and Destructors