[Lldb-commits] [PATCH] D137807: When scanning mach-o corefile, don't run all DynamicLoader plugins letting one of them Create when searching for binaries

[Jason Molenda via Phabricator via lldb-commits]

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In  https://reviews.llvm.org/D133680 I changed a lot of how ProcessMachCore scans a corefile to figure out what kind of debug session this is (kernel, firmware, userland, etc) and where the binaries are.   `ProcessMachCore::LoadBinariesViaMetadata()` calls `ObjectFile::LoadCoreFileImages()`, and under there, it is possible that the Process DynamicLoader will be set in the process of its scans.  Then back in `LoadBinariesViaMetadata()` it would check to see if the dynamic loader had been set.  It would do this by calling `ProcessMachCore::GetDynamicLoader()`, but this method, if `m_dyld_up` is empty, will call the plugin interface `FindPlugin` method with the minimal amount of information we have so far --- and pick the wrong dynamic loader plugin for a userland process.

This broke userland corefile loading in lldb; no the DynamicLoaderMacOSX plugin is not loaded, so we don't load any of the binaries in the corfile.  It's not a very commonly used type of corefile on Darwin systems, so it slipped by.  The corefiles created by lldb's `process save-core` include a lot of metadata which make this work correctly for them, so it didn't get caught by the testsuite.

The fix is to change the call to `GetDynamicLoader()` which can *set* the dynamic loader, and instead look at the ivar.  This is the only call to this method inside ProcessMachCore's methods.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D137807

Files:
  lldb/source/Plugins/Process/mach-core/ProcessMachCore.cpp


Index: lldb/source/Plugins/Process/mach-core/ProcessMachCore.cpp
===================================================================
--- lldb/source/Plugins/Process/mach-core/ProcessMachCore.cpp
+++ lldb/source/Plugins/Process/mach-core/ProcessMachCore.cpp
@@ -327,9 +327,11 @@
   // corefile
   core_objfile->LoadCoreFileImages(*this);
 
-  // LoadCoreFileImges may have set the dynamic loader; if we now have
-  // a dynamic loader, save its name so we don't un-set it later.
-  if (GetDynamicLoader())
+  // LoadCoreFileImges may have set the dynamic loader, e.g. in
+  // PlatformDarwinKernel::LoadPlatformBinaryAndSetup().
+  // If we now have a dynamic loader, save its name so we don't 
+  // un-set it later.
+  if (m_dyld_up.get())
     m_dyld_plugin_name = GetDynamicLoader()->GetPluginName();
 }
 


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