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D131437 <https://reviews.llvm.org/D131437> caused heap-use-after-free failures
when testing TestCreateAfterAttach.py in asan mode, and "regular" crashes
outside of asan.
This appears to be due to a mismatch in a couple places where we choose to
clear the DIEs. When we clear the DIE of a skeleton unit, we unconditionally
clear the DIE of the DWO unit if it exists. However, `~ScopedExtractDIEs()`
only looks at the skeleton unit when deciding to clear. If we decide to clear
the skeleton unit because it is now unused, we end up clearing the DWO unit
that _is_ used. This change adds a guard by checking `m_cancel_scopes` to
prevent clearing the DWO unit.
This is 100% reproducible by running TestCreateAfterAttach.py in asan mode,
although it only seems to reproduce in our internal build, so no test case is
added here. If someone has suggestions on how to write one, I can add it.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D133790
Files:
lldb/source/Plugins/SymbolFile/DWARF/DWARFUnit.cpp
Index: lldb/source/Plugins/SymbolFile/DWARF/DWARFUnit.cpp
===================================================================
--- lldb/source/Plugins/SymbolFile/DWARF/DWARFUnit.cpp
+++ lldb/source/Plugins/SymbolFile/DWARF/DWARFUnit.cpp
@@ -598,7 +598,7 @@
m_die_array.clear();
m_die_array.shrink_to_fit();
- if (m_dwo)
+ if (m_dwo && !m_dwo->m_cancel_scopes)
m_dwo->ClearDIEsRWLocked();
}
Index: lldb/source/Plugins/SymbolFile/DWARF/DWARFUnit.cpp
===================================================================
--- lldb/source/Plugins/SymbolFile/DWARF/DWARFUnit.cpp
+++ lldb/source/Plugins/SymbolFile/DWARF/DWARFUnit.cpp
@@ -598,7 +598,7 @@
m_die_array.clear();
m_die_array.shrink_to_fit();
- if (m_dwo)
+ if (m_dwo && !m_dwo->m_cancel_scopes)
m_dwo->ClearDIEsRWLocked();
}
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