[llvm] 762fb1c - [llvm-objcopy] Avoid invalid Sec.Offset after D79229

[Fangrui Song via llvm-commits]

Author: Fangrui Song
Date: 2020-05-03T21:57:51-07:00
New Revision: 762fb1c40eea6878c2d6a1f0f1fc7915c8747981

URL: https://github.com/llvm/llvm-project/commit/762fb1c40eea6878c2d6a1f0f1fc7915c8747981
DIFF: https://github.com/llvm/llvm-project/commit/762fb1c40eea6878c2d6a1f0f1fc7915c8747981.diff

LOG: [llvm-objcopy] Avoid invalid Sec.Offset after D79229

To avoid undefined behavior caught by -fsanitize=undefined on binary-paddr.test

  void SectionWriter::visit(const Section &Sec) {
    if (Sec.Type != SHT_NOBITS)
      // Sec.Contents is empty while Sec.Offset may be out of bound
      llvm::copy(Sec.Contents, Out.getBufferStart() + Sec.Offset);
  }

Added: 
    

Modified: 
    llvm/tools/llvm-objcopy/ELF/Object.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/tools/llvm-objcopy/ELF/Object.cpp b/llvm/tools/llvm-objcopy/ELF/Object.cpp
index f5ae3be5c516..8c3ae2596722 100644
--- a/llvm/tools/llvm-objcopy/ELF/Object.cpp
+++ b/llvm/tools/llvm-objcopy/ELF/Object.cpp
@@ -2234,11 +2234,11 @@ Error BinaryWriter::finalize() {
   // layoutSections, because we want to truncate the last segment to the end of
   // its last non-empty section, to match GNU objcopy's behaviour.
   TotalSize = 0;
-  for (SectionBase &Sec : Obj.allocSections()) {
-    Sec.Offset = Sec.Addr - MinAddr;
-    if (Sec.Type != SHT_NOBITS && Sec.Size > 0)
+  for (SectionBase &Sec : Obj.allocSections())
+    if (Sec.Type != SHT_NOBITS && Sec.Size > 0) {
+      Sec.Offset = Sec.Addr - MinAddr;
       TotalSize = std::max(TotalSize, Sec.Offset + Sec.Size);
-  }
+    }
 
   if (Error E = Buf.allocate(TotalSize))
     return E;