https://github.com/MrBoboGet created
https://github.com/llvm/llvm-project/pull/141348
lldb-dap crashes when requesting variables if the scope includes a
std::shared_ptr, as it assumes that m_ptr_obj is not null after Update. This is
however only true if Update doesn't fail for any reason, and the problem is
that LibStdcppSharedPtrSyntheticFrontEnd is used even when running on windows
and not using libstdcpp. As _M_ptr is not present in the class, so is m_ptr_obj
always null, which results in a crash when calling GetChildAtIndex with idx= 0.
This commit only fixes the crash by adding a null check, whether or not it's a
bug that LibStdcppSharedPtrSyntheticFrontEnd is used on windows at all is
difficult for me to decide, and there doesn't seem to be any support for
microsoft STL regardless.
A minimal example showcasing the bug is easy to provide:
```cpp
#include <iostream>
#include <memory>
int main(int arg, char** argv)
{
std::shared_ptr<int> broken = std::make_shared<int>();
std::cout<<"Hello world!"<<std::endl;
}
```
Compiling the above with clang++ and setting a breakpoint before printing hello
world and debugging should produce the crash on all DAP clients running on
windows.
>From 042b2a6b2e9513fcd8aba84082aa019b0178b994 Mon Sep 17 00:00:00 2001
From: MrBoboGet <emanuelberggre...@gmail.com>
Date: Sat, 24 May 2025 16:41:08 +0200
Subject: [PATCH] [LLDB] Fix std::shared_ptr formatter crash on windows
---
lldb/source/Plugins/Language/CPlusPlus/LibStdcpp.cpp | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/lldb/source/Plugins/Language/CPlusPlus/LibStdcpp.cpp
b/lldb/source/Plugins/Language/CPlusPlus/LibStdcpp.cpp
index 02113baf64b8c..54158d9a0d85a 100644
--- a/lldb/source/Plugins/Language/CPlusPlus/LibStdcpp.cpp
+++ b/lldb/source/Plugins/Language/CPlusPlus/LibStdcpp.cpp
@@ -379,7 +379,7 @@ LibStdcppSharedPtrSyntheticFrontEnd::CalculateNumChildren()
{
lldb::ValueObjectSP
LibStdcppSharedPtrSyntheticFrontEnd::GetChildAtIndex(uint32_t idx) {
- if (idx == 0)
+ if (idx == 0 && m_ptr_obj)
return m_ptr_obj->GetSP();
if (idx == 1) {
if (m_ptr_obj && !m_obj_obj) {
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