[PATCH] D121398: Return an error when dsymutil might produce an invalid mach-o file.

[Greg Clayton via Phabricator via llvm-commits]

clayborg created this revision.
clayborg added reviewers: JDevlieghere, aprantl.
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64 bit mach-o files have sections that only have 32 bit file offsets. If dsymutil tries to produce an invalid mach-o file, then error out with a good error string.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D121398

Files:
  llvm/tools/dsymutil/MachOUtils.cpp


Index: llvm/tools/dsymutil/MachOUtils.cpp
===================================================================
--- llvm/tools/dsymutil/MachOUtils.cpp
+++ llvm/tools/dsymutil/MachOUtils.cpp
@@ -304,7 +304,7 @@
 }
 
 // Write the __DWARF segment load command to the output file.
-static void createDwarfSegment(uint64_t VMAddr, uint64_t FileOffset,
+static bool createDwarfSegment(uint64_t VMAddr, uint64_t FileOffset,
                                uint64_t FileSize, unsigned NumSections,
                                MCAsmLayout &Layout, MachObjectWriter &Writer) {
   Writer.writeSegmentLoadCommand("__DWARF", NumSections, VMAddr,
@@ -321,12 +321,15 @@
     if (Align > 1) {
       VMAddr = alignTo(VMAddr, Align);
       FileOffset = alignTo(FileOffset, Align);
+      if (FileOffset > UINT32_MAX)
+        return error("section " + Sec->getName() + "'s file offset exceeds 4GB and will produce an invalid mach-o file");
     }
     Writer.writeSection(Layout, *Sec, VMAddr, FileOffset, 0, 0, 0);
 
     FileOffset += Layout.getSectionAddressSize(Sec);
     VMAddr += Layout.getSectionAddressSize(Sec);
   }
+  return true;
 }
 
 static bool isExecutable(const object::MachOObjectFile &Obj) {
@@ -564,8 +567,9 @@
   }
 
   // Write the load command for the __DWARF segment.
-  createDwarfSegment(DwarfVMAddr, DwarfSegmentStart, DwarfSegmentSize,
-                     NumDwarfSections, Layout, Writer);
+  if (!createDwarfSegment(DwarfVMAddr, DwarfSegmentStart, DwarfSegmentSize,
+                          NumDwarfSections, Layout, Writer))
+    return false;
 
   assert(OutFile.tell() == LoadCommandSize + HeaderSize);
   OutFile.write_zeros(SymtabStart - (LoadCommandSize + HeaderSize));


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