Fix a potential illegal memory access by objcopy when extracting dwo sections.

PR 26805
 * objcopy.c (is_dwo_section): Check for missing or short section
 names.

binutils/ChangeLog

@@ -1,3 +1,9 @@
+2020-10-29  Nick Clifton  <nickc@redhat.com>
+
+	PR 26805
+	* objcopy.c (is_dwo_section): Check for missing or short section
+	names.
+
 2020-10-26  Andreas Rammhold <andreas@rammhold.de>
 
 	* README-how-to-make-a-release: Use sha256sum instead of md5sum.

binutils/objcopy.c

@@ -1268,8 +1268,15 @@ group_signature (asection *group)
 static bfd_boolean
 is_dwo_section (bfd *abfd ATTRIBUTE_UNUSED, asection *sec)
 {
-  const char *name = bfd_section_name (sec);
-  int len = strlen (name);
+  const char *name;
+  int len;
+
+  if (sec == NULL || (name = bfd_section_name (sec)) == NULL)
+    return FALSE;
+
+  len = strlen (name);
+  if (len < 5)
+    return FALSE;
 
   return strncmp (name + len - 4, ".dwo", 4) == 0;
 }