[Lldb-commits] [lldb] f2f9459 - [lldb] Protect frame provider construction from re-entrant frame access

[Med Ismail Bennani via lldb-commits]

Author: Med Ismail Bennani
Date: 2026-03-25T23:20:33-07:00
New Revision: f2f94597671f897dc939facd756f0be58fdf017e

URL: https://github.com/llvm/llvm-project/commit/f2f94597671f897dc939facd756f0be58fdf017e
DIFF: https://github.com/llvm/llvm-project/commit/f2f94597671f897dc939facd756f0be58fdf017e.diff

LOG: [lldb] Protect frame provider construction from re-entrant frame access

When a scripted frame provider calls HandleCommand or other
frame-accessing APIs during __init__, GetStackFrameList() re-enters
without the re-entrancy guard, causing infinite recursion. On Windows
(1MB default stack), this results in a stack overflow (0xC00000FD)
before Python's recursion limit can intervene.

The existing PushProviderFrameList/PopProviderFrameList guard only
protected GetFrameAtIndex calls in FetchFramesUpTo. This wraps the
CreateInstance call in LoadScriptedFrameProvider with the same guard
so that provider construction is also protected.

Signed-off-by: Med Ismail Bennani <ismail at bennani.ma>

Added: 
    

Modified: 
    lldb/source/Target/Thread.cpp

Removed: 
    


################################################################################
diff  --git a/lldb/source/Target/Thread.cpp b/lldb/source/Target/Thread.cpp
index 6ecca96ebb02e..9e977481546b9 100644
--- a/lldb/source/Target/Thread.cpp
+++ b/lldb/source/Target/Thread.cpp
@@ -1632,8 +1632,15 @@ llvm::Error Thread::LoadScriptedFrameProvider(
         last_id);
   }
 
+  // Protect provider construction (__init__) from re-entrancy. If the
+  // provider calls back into the frame machinery (e.g. HandleCommand("bt"))
+  // during __init__, GetStackFrameList() will find this thread in the
+  // active-provider map and return input_frames instead of trying to
+  // build a new synthetic list — preventing infinite recursion.
+  PushProviderFrameList(input_frames);
   auto provider_or_err =
       SyntheticFrameProvider::CreateInstance(input_frames, descriptor);
+  PopProviderFrameList();
   if (!provider_or_err)
     return provider_or_err.takeError();