[PATCH] D130288: [lld-macho] Fix LOH parsing segfault

[Jez Ng via Phabricator via llvm-commits]

int3 created this revision.
int3 added a reviewer: lld-macho.
Herald added projects: lld-macho, All.
int3 requested review of this revision.
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Herald added a subscriber: llvm-commits.

`advanceSubsection()` didn't account for the possibility that a section
could have no subsections.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D130288

Files:
  lld/MachO/InputFiles.cpp
  lld/test/MachO/loh-parsing.s


Index: lld/test/MachO/loh-parsing.s
===================================================================
--- /dev/null
+++ lld/test/MachO/loh-parsing.s
@@ -0,0 +1,20 @@
+# REQUIRES: aarch64
+
+# RUN: llvm-mc -filetype=obj -triple=arm64-apple-darwin %s -o %t.o
+# RUN: %lld -arch arm64 -dylib %t.o -o /dev/null
+
+## Check that we parse the LOH / match it to its referent sections correctly,
+## even when there are other subsections that don't get parsed as regular
+## sections. (We would previously segfault.)
+## `__objc_imageinfo` is one such section that gets special-case handling.
+
+.section __DATA,__objc_imageinfo,regular,no_dead_strip
+.long 0
+.long 0x40
+
+.section __TEXT,__StaticInit
+_bar:
+L1:  adrp  x1, _foo at PAGE
+L2:  ldr   x1, [x1, _foo at PAGEOFF]
+
+.loh AdrpLdr L1, L2
Index: lld/MachO/InputFiles.cpp
===================================================================
--- lld/MachO/InputFiles.cpp
+++ lld/MachO/InputFiles.cpp
@@ -563,7 +563,7 @@
     if (section == sections.end())
       return;
     ++subsection;
-    if (subsection == (*section)->subsections.end()) {
+    while (subsection == (*section)->subsections.end()) {
       ++section;
       if (section == sections.end())
         return;
@@ -585,6 +585,7 @@
         if (section == sections.end())
           break;
         updateAddr();
+        assert(hintStart->offset0 >= subsectionBase);
       }
     }
 


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