[Lldb-commits] [lldb] [lldb] Fix wrong buffer size when fetching Objective-C classes (PR #197389)

[Raphael Isemann via lldb-commits]

https://github.com/Teemperor updated https://github.com/llvm/llvm-project/pull/197389

>From 4f7ea26ce7b6e767e81ad3bf339d60737375665e Mon Sep 17 00:00:00 2001
From: Raphael Isemann <rise at apple.com>
Date: Wed, 13 May 2026 09:37:16 +0100
Subject: [PATCH] [lldb] Fix wrong buffer size when fetching Objective-C
 classes

LLDB calls objc_getRealizedClassList_trylock to fetch the list of
realized Objective-C classes.

Jim spotted that we currently pass the buffer length in *bytes*, when
actually this API takes the buffer length in number of elements. This
causes that the Objective-C runtime write more memory that we allocated
for it. This can cause that the function calling expression crashes
and leaves the Objective-C runtime mutex locked.
---
 .../ObjC/AppleObjCRuntime/AppleObjCRuntimeV2.cpp                | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lldb/source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCRuntimeV2.cpp b/lldb/source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCRuntimeV2.cpp
index 4ca179d927427..d6a0dd8a4b37b 100644
--- a/lldb/source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCRuntimeV2.cpp
+++ b/lldb/source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCRuntimeV2.cpp
@@ -2245,7 +2245,7 @@ AppleObjCRuntimeV2::DynamicClassInfoExtractor::UpdateISAToDescriptorMap(
 
   if (class_buffer_addr != LLDB_INVALID_ADDRESS) {
     arguments.GetValueAtIndex(index++)->GetScalar() = class_buffer_addr;
-    arguments.GetValueAtIndex(index++)->GetScalar() = class_buffer_byte_size;
+    arguments.GetValueAtIndex(index++)->GetScalar() = class_buffer_len;
   }
 
   // Only dump the runtime classes from the expression evaluation if the log is