[Lldb-commits] [PATCH] D144528: [lldb] Warn when Mach-O files have overlapping segments

Alex Langford via Phabricator via lldb-commits lldb-commits at lists.llvm.org
Tue Feb 21 18:17:47 PST 2023

bulbazord created this revision.
bulbazord added reviewers: jasonmolenda, jingham, mib.
Herald added a project: All.
bulbazord requested review of this revision.
Herald added a project: LLDB.
Herald added a subscriber: lldb-commits.

I recently came across a binary that for some reason had overlapping
sections. When debugging it, LLDB was able to get information about one
of the sections but not the other because SectionLoadList assumes that
each address maps to exactly one section. We have the capability to warn
about this, but it was not turned on.


  rG LLVM Github Monorepo



Index: lldb/source/Plugins/ObjectFile/Mach-O/ObjectFileMachO.cpp
--- lldb/source/Plugins/ObjectFile/Mach-O/ObjectFileMachO.cpp
+++ lldb/source/Plugins/ObjectFile/Mach-O/ObjectFileMachO.cpp
@@ -6182,6 +6182,10 @@
   size_t num_loaded_sections = 0;
   const size_t num_sections = section_list->GetSize();
+  // Warn if some top-level segments map to the same address. The binary may be
+  // malformed.
+  const bool warn_multiple = true;
   if (value_is_offset) {
     // "value" is an offset to apply to each top level segment
     for (size_t sect_idx = 0; sect_idx < num_sections; ++sect_idx) {
@@ -6190,7 +6194,8 @@
       SectionSP section_sp(section_list->GetSectionAtIndex(sect_idx));
       if (SectionIsLoadable(section_sp.get()))
         if (target.GetSectionLoadList().SetSectionLoadAddress(
-                section_sp, section_sp->GetFileAddress() + value))
+                section_sp, section_sp->GetFileAddress() + value,
+                warn_multiple))
   } else {
@@ -6207,7 +6212,7 @@
                 value, mach_header_section, section_sp.get());
         if (section_load_addr != LLDB_INVALID_ADDRESS) {
           if (target.GetSectionLoadList().SetSectionLoadAddress(
-                  section_sp, section_load_addr))
+                  section_sp, section_load_addr, warn_multiple))

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