Re: Bug 23686, two segment faults in nm

The fix for pr23686 had a hole in the reloc address sanity check,
the calculation could overflow.  Note that stabsize is known to be a
non-zero multiple of 12 so stabsize - 4 can't underflow.

	PR 23686
	* syms.c (_bfd_stab_section_find_nearest_line): Correct
	r->address sanity check.

bfd/syms.c

@@ -1106,7 +1106,7 @@ _bfd_stab_section_find_nearest_line (bfd *abfd,
 		  || r->howto->pc_relative
 		  || r->howto->bitpos != 0
 		  || r->howto->dst_mask != 0xffffffff
-		  || octets + 4 > stabsize)
+		  || octets > stabsize - 4)
 		{
 		  _bfd_error_handler
 		    (_("unsupported .stab relocation"));