Call last_component instead of base_name. The latter returns a malloced string since 2006-03-11.

src/extract.c

@@ -871,7 +871,7 @@ create_placeholder_file (char *file_name, bool is_symlink, int *interdir_made)
       if (h && ! h->after_links
 	  && strncmp (file_name, h->file_name, h->file_name_len) == 0
 	  && ISSLASH (file_name[h->file_name_len])
-	  && (base_name (file_name) == file_name + h->file_name_len + 1))
+	  && (last_component (file_name) == file_name + h->file_name_len + 1))
 	{
 	  do
 	    {

src/xheader.c

@@ -264,7 +264,7 @@ xheader_format_name (struct tar_stat_info *st, const char *fmt, size_t n)
 	case 'f':
 	  if (st)
 	    {
-	      base = base_name (st->orig_file_name);
+	      base = last_component (st->orig_file_name);
 	      len += strlen (base) - 2;
 	    }
 	  break;