Fix potential buffer overrun whilst scanning macro strings.

PR 24010
	* macro.c (get_any_string): Check for end of input whilst scanning
	for separators.

gas/macro.c

@@ -369,7 +369,7 @@ get_any_string (size_t idx, sb *in, sb *out)
     {
       if (in->len > idx + 2 && in->ptr[idx + 1] == '\'' && ISBASE (in->ptr[idx]))
 	{
-	  while (!ISSEP (in->ptr[idx]))
+	  while (idx < in->len && !ISSEP (in->ptr[idx]))
 	    sb_add_char (out, in->ptr[idx++]);
 	}
       else if (in->ptr[idx] == '%' && macro_alternate)