[Lldb-commits] [lldb] 9c254f1 - [lldb] Fix heap.py crashes on recent Darwin embedded targets

[Med Ismail Bennani via lldb-commits]

Author: Med Ismail Bennani
Date: 2026-03-14T04:02:21-07:00
New Revision: 9c254f182517a9bce0017beb575706004f978f23

URL: https://github.com/llvm/llvm-project/commit/9c254f182517a9bce0017beb575706004f978f23
DIFF: https://github.com/llvm/llvm-project/commit/9c254f182517a9bce0017beb575706004f978f23.diff

LOG: [lldb] Fix heap.py crashes on recent Darwin embedded targets

Two fixes for the ptr_refs/cstr_refs/find_variable heap commands:

1. Move the `task` variable declaration into the common expression
  preamble. Previously it was only declared inside the `search_heap`
  code path, causing compilation errors when using `--ignore-heap`
  with stack or segment scanning.

2. On recent iOS, some shared cache __DATA_CONST pages are remapped to
  non-accessible at runtime, even though the Mach-O section metadata
  still marks them as readable. The segment scan would crash with
  EXC_BAD_ACCESS when reading these pages. Fix by querying actual
  VM region permissions via SBProcess.GetMemoryRegionInfo() and
  splitting sections at region boundaries to only scan readable
  portions.

rdar://172543652

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

Added: 
    

Modified: 
    lldb/examples/darwin/heap_find/heap.py

Removed: 
    


################################################################################
diff  --git a/lldb/examples/darwin/heap_find/heap.py b/lldb/examples/darwin/heap_find/heap.py
index e575be56b29c0..3ba349703c21d 100644
--- a/lldb/examples/darwin/heap_find/heap.py
+++ b/lldb/examples/darwin/heap_find/heap.py
@@ -32,6 +32,7 @@ def get_iterate_memory_expr(options, process, user_init_code, user_return_code):
 typedef int kern_return_t;
 #define KERN_SUCCESS 0
 typedef void (*range_callback_t)(task_t, void *, unsigned, uintptr_t, uintptr_t);
+task_t task = 0;
 """
     if options.search_vm_regions:
         expr += """
@@ -130,7 +131,7 @@ def get_iterate_memory_expr(options, process, user_init_code, user_return_code):
     return KERN_SUCCESS;
 };
 vm_address_t *zones = 0;
-unsigned int num_zones = 0;task_t task = 0;
+unsigned int num_zones = 0;
 kern_return_t err = (kern_return_t)malloc_get_all_zones (task, task_peek, &zones, &num_zones);
 if (KERN_SUCCESS == err)
 {
@@ -1305,7 +1306,24 @@ def get_sections_ranges_struct(process):
                 base = section.GetLoadAddress(target)
                 size = section.GetByteSize()
                 if base != lldb.LLDB_INVALID_ADDRESS and size > 0:
-                    segment_dicts.append({"base": base, "size": size})
+                    # Walk VM regions across the section and only include
+                    # readable portions, since runtime permissions may
+                    # 
diff er from the Mach-O section permissions.
+                    addr = base
+                    end = base + size
+                    while addr < end:
+                        region_info = lldb.SBMemoryRegionInfo()
+                        if not process.GetMemoryRegionInfo(addr, region_info).Success():
+                            break
+                        region_end = region_info.GetRegionEnd()
+                        if region_end <= addr:
+                            break
+                        chunk_end = min(region_end, end)
+                        if region_info.IsReadable():
+                            segment_dicts.append(
+                                {"base": addr, "size": chunk_end - addr}
+                            )
+                        addr = chunk_end
     segment_dicts_len = len(segment_dicts)
     if segment_dicts_len > 0:
         result = """