From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935204AbcIPOrp (ORCPT ); Fri, 16 Sep 2016 10:47:45 -0400 Received: from mail-pa0-f66.google.com ([209.85.220.66]:34749 "EHLO mail-pa0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935339AbcIPOrG (ORCPT ); Fri, 16 Sep 2016 10:47:06 -0400 From: Stafford Horne To: Jonas Bonn , Stefan Kristiansson , Andrew Morton Cc: linux-kernel@vger.kernel.org, Stafford Horne Subject: [PATCH 1/7] Apply transparent_union attribute to union semun Date: Fri, 16 Sep 2016 23:42:59 +0900 Message-Id: <1474036985-20981-2-git-send-email-shorne@gmail.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1474036985-20981-1-git-send-email-shorne@gmail.com> References: <1474036985-20981-1-git-send-email-shorne@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Jonas Bonn The syscall handler for semctl is written under the assumption that the toolchain will pass "small" unions as function parameters directly instead of by reference. The union semun is "small" and thus fits this description. Since it is assumed that the union will be passed directly and not by reference, it is safe to access the union members without going via get_user. The OpenRISC architecture, however, passes all unions by reference, thus breaking the above assumption. The technically correct fix here is to mark the union as being transparent so that the ABI of the union's first element determines the parameter passing method and thus make explicit what's already implied in the function definition. Signed-off-by: Jonas Bonn Signed-off-by: Stafford Horne --- include/uapi/linux/sem.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/include/uapi/linux/sem.h b/include/uapi/linux/sem.h index dd73b90..aabe50f 100644 --- a/include/uapi/linux/sem.h +++ b/include/uapi/linux/sem.h @@ -48,7 +48,7 @@ union semun { unsigned short __user *array; /* array for GETALL & SETALL */ struct seminfo __user *__buf; /* buffer for IPC_INFO */ void __user *__pad; -}; +} __attribute__ ((transparent_union)); struct seminfo { int semmap; -- 2.7.4