Fix a seg-fault when displaying notes from a prorgam segment. Check for a NULL string section before attempting compute the name of a separate debug info file.

	PR 22490
	* readelf.c (dump_section_as_bytes): Check for a NULL string
	section pointer.
	(process_notes_at): Compute the alignment to use if displaying
	notes from a segment.

2 files changed, 29 insertions, 11 deletions

diff --git a/binutils/ChangeLog b/binutils/ChangeLog
index 75ef5cd0321..f30ef1970f1 100644
--- a/binutils/ChangeLog
+++ b/binutils/ChangeLog
@@ -1,3 +1,11 @@
+2017-11-27  Nick Clifton  <nickc@redhat.com>
+
+	PR 22490
+	* readelf.c (dump_section_as_bytes): Check for a NULL string
+	section pointer.
+	(process_notes_at): Compute the alignment to use if displaying
+	notes from a segment.
+
 2017-11-26  H.J. Lu  <hongjiu.lu@intel.com>
 
 	* dwarf.c (load_separate_debug_info): Rename argument name from
diff --git a/binutils/readelf.c b/binutils/readelf.c
index 739367d899b..53896ae647b 100644
--- a/binutils/readelf.c
+++ b/binutils/readelf.c
@@ -13581,7 +13581,7 @@ load_debug_section (enum dwarf_section_display_enum debug, void * data)
       /* Read in the string table, so that we have section names to scan.  */
       strs = filedata->section_headers + filedata->file_header.e_shstrndx;
 
-      if (strs->sh_size != 0)
+      if (strs != NULL && strs->sh_size != 0)
 	{
 	  filedata->string_table = (char *) get_data (NULL, filedata, strs->sh_offset,
 						      1, strs->sh_size,
@@ -17908,8 +17908,9 @@ process_notes_at (Filedata *           filedata,
 {
   Elf_External_Note * pnotes;
   Elf_External_Note * external;
-  char * end;
-  bfd_boolean res = TRUE;
+  char *              end;
+  bfd_boolean         res = TRUE;
+  size_t              align;
 
   if (length <= 0)
     return FALSE;
@@ -17922,10 +17923,21 @@ process_notes_at (Filedata *           filedata,
 	  if (! apply_relocations (filedata, section, (unsigned char *) pnotes, length, NULL, NULL))
 	    return FALSE;
 	}
+      align = section->sh_addralign;
     }
   else
-    pnotes = (Elf_External_Note *) get_data (NULL, filedata, offset, 1, length,
+    {
+      pnotes = (Elf_External_Note *) get_data (NULL, filedata, offset, 1, length,
 					     _("notes"));
+
+      /* FIXME: Core notes seem to be produced with
+	 4-byte alignment even on 64-bit systems.  */
+      if (filedata->file_header.e_type == ET_CORE)
+	align = 4;
+      else
+	align = is_32bit_elf ? 4 : 4;
+    }
+
   if (pnotes == NULL)
     return FALSE;
 
@@ -17944,7 +17956,7 @@ process_notes_at (Filedata *           filedata,
     {
       Elf_Internal_Note inote;
       size_t min_notesz;
-      char *next;
+      char * next;
       char * temp = NULL;
       size_t data_remaining = end - (char *) external;
 
@@ -17970,12 +17982,10 @@ process_notes_at (Filedata *           filedata,
 	  inote.namedata = external->name;
 	  inote.descsz   = BYTE_GET (external->descsz);
 	  inote.descdata = ((char *) external
-			    + ELF_NOTE_DESC_OFFSET (inote.namesz,
-						    section->sh_addralign));
+			    + ELF_NOTE_DESC_OFFSET (inote.namesz, align));
 	  inote.descpos  = offset + (inote.descdata - (char *) pnotes);
 	  next = ((char *) external
-		  + ELF_NOTE_NEXT_OFFSET (inote.namesz, inote.descsz,
-					  section->sh_addralign));
+		  + ELF_NOTE_NEXT_OFFSET (inote.namesz, inote.descsz, align));
 	}
       else
 	{
@@ -18016,8 +18026,8 @@ process_notes_at (Filedata *           filedata,
 	{
 	  warn (_("note with invalid namesz and/or descsz found at offset 0x%lx\n"),
 		(unsigned long) ((char *) external - (char *) pnotes));
-	  warn (_(" type: 0x%lx, namesize: 0x%08lx, descsize: 0x%08lx\n"),
-		inote.type, inote.namesz, inote.descsz);
+	  warn (_(" type: 0x%lx, namesize: 0x%08lx, descsize: 0x%08lx, alignment: %u\n"),
+		inote.type, inote.namesz, inote.descsz, (int) align);
 	  break;
 	}