[Lldb-commits] [lldb] 861adf6 - [lldb] Fix heap-use-after-free in FileSpec usage (#211908)

[via lldb-commits]

Author: Jordan Rupprecht
Date: 2026-07-24T20:57:47-05:00
New Revision: 861adf6f34727fbcc66c64ddba916ac0bb0423c2

URL: https://github.com/llvm/llvm-project/commit/861adf6f34727fbcc66c64ddba916ac0bb0423c2
DIFF: https://github.com/llvm/llvm-project/commit/861adf6f34727fbcc66c64ddba916ac0bb0423c2.diff

LOG: [lldb] Fix heap-use-after-free in FileSpec usage (#211908)

After #211394, `FileSpec` stores m_filename as a `SmallString` instead
of `ConstString`. When the `FileSpec` goes out of scope / is destructed,
a `StringRef` pointing to m_filename is now invalid. Previously it would
have worked even after `FileSpec` goes out of scope since `ConstString`
stores the string in a global buffer which is never destructed.

This causes heap-use-after-free in `CommandInterpreter` when we use the
result of `GetFilename()` on a temporary `FileSpec`. Store the result of
`HostInfo::GetProgramFileSpec()` as a variable to prevent it from going
out of scope before we're able to call `GetHomeInitFile()`.

Although #211394 introduces this failure, technically speaking this is
an existing bug, it was just masked because of how `FileSpec` used to
use `ConstString` to force a long lifetime.

Added: 
    

Modified: 
    lldb/source/Interpreter/CommandInterpreter.cpp

Removed: 
    


################################################################################
diff  --git a/lldb/source/Interpreter/CommandInterpreter.cpp b/lldb/source/Interpreter/CommandInterpreter.cpp
index 8627329caa4da..12578ca56a967 100644
--- a/lldb/source/Interpreter/CommandInterpreter.cpp
+++ b/lldb/source/Interpreter/CommandInterpreter.cpp
@@ -2728,7 +2728,8 @@ void CommandInterpreter::SourceInitFileHome(CommandReturnObject &result,
     GetHomeInitFile(init_file);
 
   if (!m_skip_app_init_files) {
-    llvm::StringRef program_name = HostInfo::GetProgramFileSpec().GetFilename();
+    FileSpec program_file_spec = HostInfo::GetProgramFileSpec();
+    llvm::StringRef program_name = program_file_spec.GetFilename();
     FileSpec program_init_file;
     GetHomeInitFile(program_init_file, program_name);
     if (FileSystem::Instance().Exists(program_init_file))