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Re: PowerPC64 toc edit segfault


On Wed, Feb 09, 2011 at 06:50:28PM +1030, Alan Modra wrote:
> This fixes two segfaults in ppc64_elf_edit_toc, found when simply

> @@ -8418,15 +8424,9 @@ ppc64_elf_edit_toc (struct bfd_link_info
>  	      Elf_Internal_Rela *wrel;
>  	      bfd_size_type sz;
>  
> -	      /* Read toc relocs.  */
> -	      relstart = _bfd_elf_link_read_relocs (ibfd, toc, NULL, NULL,
> -						    TRUE);
> -	      if (relstart == NULL)
> -		goto error_ret;
> -
>  	      /* Remove unused toc relocs, and adjust those we keep.  */
> -	      wrel = relstart;
> -	      for (rel = relstart; rel < relstart + toc->reloc_count; ++rel)
> +	      wrel = toc_relocs;
> +	      for (rel = toc_relocs; rel < toc_relocs + toc->reloc_count; ++rel)
>  		if ((skip[rel->r_offset >> 3]
>  		     & (ref_from_discarded | can_optimize)) == 0)
>  		  {

Blah.  Removing the above "Read toc relocs" caused a segfault when
linking -mcmodel=small code.

	* elf64-ppc.c (ppc64_elf_edit_toc): Reinstate second read of
	toc relocs.  Fuss over free(NULL).

Index: bfd/elf64-ppc.c
===================================================================
RCS file: /cvs/src/src/bfd/elf64-ppc.c,v
retrieving revision 1.342
diff -u -p -r1.342 elf64-ppc.c
--- bfd/elf64-ppc.c	9 Feb 2011 08:16:00 -0000	1.342
+++ bfd/elf64-ppc.c	15 Feb 2011 03:54:10 -0000
@@ -8424,6 +8424,12 @@ ppc64_elf_edit_toc (struct bfd_link_info
 	      bfd_size_type sz;
 
 	      /* Remove unused toc relocs, and adjust those we keep.  */
+	      if (toc_relocs == NULL)
+		toc_relocs = _bfd_elf_link_read_relocs (ibfd, toc, NULL, NULL,
+							info->keep_memory);
+	      if (toc_relocs == NULL)
+		goto error_ret;
+
 	      wrel = toc_relocs;
 	      for (rel = toc_relocs; rel < toc_relocs + toc->reloc_count; ++rel)
 		if ((skip[rel->r_offset >> 3]
@@ -8445,7 +8451,8 @@ ppc64_elf_edit_toc (struct bfd_link_info
 	      rel_hdr->sh_size = toc->reloc_count * sz;
 	    }
 	}
-      else if (elf_section_data (toc)->relocs != toc_relocs)
+      else if (toc_relocs != NULL
+	       && elf_section_data (toc)->relocs != toc_relocs)
 	free (toc_relocs);
 
       if (local_syms != NULL

-- 
Alan Modra
Australia Development Lab, IBM


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