[lldb] [Mach-O corefiles] Sanity check malformed dyld

lldb scans the corefile for dyld, the dynamic loader, and when it
finds a mach-o header that looks like dyld, it tries to read all
of the load commands and symbol table out of the corefile memory.
If the load comamnds and symbol table are absent or malformed,
it doesn't handle this case and can crash.  Back out when we
fail to create a Module from the dyld binary.

rdar://136659551

Author: jasonmolenda

lldb/source/Plugins/DynamicLoader/MacOSX-DYLD/DynamicLoaderDarwin.cpp

@@ -594,7 +594,7 @@ void DynamicLoaderDarwin::UpdateSpecialBinariesFromNewImageInfos(
   }
 }
 
-void DynamicLoaderDarwin::UpdateDYLDImageInfoFromNewImageInfo(
+bool DynamicLoaderDarwin::UpdateDYLDImageInfoFromNewImageInfo(
     ImageInfo &image_info) {
   if (image_info.header.filetype == llvm::MachO::MH_DYLINKER) {
     const bool can_create = true;
@@ -605,8 +605,10 @@ void DynamicLoaderDarwin::UpdateDYLDImageInfoFromNewImageInfo(
       target.GetImages().AppendIfNeeded(dyld_sp);
       UpdateImageLoadAddress(dyld_sp.get(), image_info);
       SetDYLDModule(dyld_sp);
+      return true;
     }
   }
+  return false;
 }
 
 std::optional<lldb_private::Address> DynamicLoaderDarwin::GetStartAddress() {

lldb/source/Plugins/DynamicLoader/MacOSX-DYLD/DynamicLoaderDarwin.h

@@ -208,7 +208,7 @@ class DynamicLoaderDarwin : public lldb_private::DynamicLoader {
   UpdateSpecialBinariesFromNewImageInfos(ImageInfo::collection &image_infos);
 
   // if image_info is a dyld binary, call this method
-  void UpdateDYLDImageInfoFromNewImageInfo(ImageInfo &image_info);
+  bool UpdateDYLDImageInfoFromNewImageInfo(ImageInfo &image_info);
 
   // If image_infos contains / may contain executable image, call this method
   // to keep our internal record keeping of the special dyld binary up-to-date.

lldb/source/Plugins/DynamicLoader/MacOSX-DYLD/DynamicLoaderMacOSXDYLD.cpp

@@ -259,10 +259,13 @@ bool DynamicLoaderMacOSXDYLD::ReadDYLDInfoFromMemoryAndSetNotificationCallback(
       ModuleSP dyld_module_sp;
       if (ParseLoadCommands(data, m_dyld, &m_dyld.file_spec)) {
         if (m_dyld.file_spec) {
-          UpdateDYLDImageInfoFromNewImageInfo(m_dyld);
+          if (!UpdateDYLDImageInfoFromNewImageInfo(m_dyld))
+            return false;
         }
       }
       dyld_module_sp = GetDYLDModule();
+      if (!dyld_module_sp)
+        return false;
 
       Target &target = m_process->GetTarget();