Fix stripping relocs in a file with mergeable notes.

A recent Fedora bug (1520805) exposed a problem with objcopy's reloc
  copying code, when a binary also contains mergeable notes.  The note
  merging code would delete some relocs, but then the reloc copying code
  would try to put them back again, which did not work.

  So I am checking in the patch below to fix the problem.  The patch
  also tweaks one of the binutils note merging tests so that it is
  skipped for the Sparc64 target, since this has funky relocs.

binutils	* objcopy.c (copy_relocations_in_section): Use the orelocations
	field of the input section, if it has been initialised.
	* testsuite/binutils-all/note-2-64.d: Skip test on Sparc64.

bfd	* elfcode.h (elf_write_relocs): Check for an empty howto field.

bfd/ChangeLog

@@ -1,3 +1,7 @@
+2017-12-08  Nick Clifton  <nickc@redhat.com>
+
+	* elfcode.h (elf_write_relocs): Check for an empty howto field.
+
 2017-12-08  Sangamesh Mallayya  <sangamesh.swamy@in.ibm.com>
 
 	* bfd.c (bfd_get_sign_extend_vma): Handle aix5coff64-rs6000.

bfd/elfcode.h

@@ -958,6 +958,12 @@ elf_write_relocs (bfd *abfd, asection *sec, void *data)
 	  return;
 	}
 
+      if (ptr->howto == NULL)
+	{
+	  *failedp = TRUE;
+	  return;
+	}
+
       src_rela.r_offset = ptr->address + addr_offset;
       src_rela.r_info = ELF_R_INFO (n, ptr->howto->type);
       src_rela.r_addend = ptr->addend;

binutils/ChangeLog

@@ -1,3 +1,9 @@
+2017-12-08  Nick Clifton  <nickc@redhat.com>
+
+	* objcopy.c (copy_relocations_in_section): Use the orelocations
+	field of the input section, if it has been initialised.
+	* testsuite/binutils-all/note-2-64.d: Skip test on Sparc64.
+
 2017-12-06  Jim Wilson  <jimw@sifive.com>
 
 	PR 22465

binutils/objcopy.c

@@ -3785,14 +3785,24 @@ copy_relocations_in_section (bfd *ibfd, sec_ptr isection, void *obfdarg)
     }
   else
     {
-      relpp = (arelent **) xmalloc (relsize);
-      relcount = bfd_canonicalize_reloc (ibfd, isection, relpp, isympp);
-      if (relcount < 0)
+      if (isection->orelocation != NULL)
 	{
-	  status = 1;
-	  bfd_nonfatal_message (NULL, ibfd, isection,
-				_("relocation count is negative"));
-	  return;
+	  /* Some other function has already set up the output relocs
+	     for us, so scan those instead of the default relocs.  */
+	  relcount = isection->reloc_count;
+	  relpp = isection->orelocation;
+	}
+      else
+	{
+	  relpp = (arelent **) xmalloc (relsize);
+	  relcount = bfd_canonicalize_reloc (ibfd, isection, relpp, isympp);
+	  if (relcount < 0)
+	    {
+	      status = 1;
+	      bfd_nonfatal_message (NULL, ibfd, isection,
+				    _("relocation count is negative"));
+	      return;
+	    }
 	}
 
       if (strip_symbols == STRIP_ALL)
@@ -3815,7 +3825,8 @@ copy_relocations_in_section (bfd *ibfd, sec_ptr isection, void *obfdarg)
 		  temp_relpp [temp_relcount++] = relpp [i];
 	    }
 	  relcount = temp_relcount;
-	  free (relpp);
+	  if (isection->orelocation == NULL)
+	    free (relpp);
 	  relpp = temp_relpp;
 	}
 

binutils/testsuite/binutils-all/note-2-64.d

@@ -3,6 +3,10 @@
 #objcopy: --merge-notes
 #name: merge notes section (64-bits)
 #source: note-2-64.s
+#not-target: sparc64-*-*
+# Internally the Sparc64 backend uses two relocs for every one reloc visible externally.
+# Unfortunately the BFD library does not provide a target specific way to delete individual
+# relocs, so the note merging feature fails.
 
 #...
   Owner                 Data size	Description