From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754883AbbL3NYe (ORCPT ); Wed, 30 Dec 2015 08:24:34 -0500 Received: from mail-pa0-f49.google.com ([209.85.220.49]:36424 "EHLO mail-pa0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754863AbbL3NY2 (ORCPT ); Wed, 30 Dec 2015 08:24:28 -0500 Subject: Re: [PATCH v2 2/2] ppdev: add support for compat ioctl To: Sudip Mukherjee , Arnd Bergmann References: <1450346332-31830-1-git-send-email-bamvor.zhangjian@linaro.org> <1450346332-31830-3-git-send-email-bamvor.zhangjian@linaro.org> <2687762.Ja01N3hBuT@wuerfel> <20151230111648.GA29697@sudip-pc> Cc: linux-kernel@vger.kernel.org, y2038@lists.linaro.org, gregkh@linuxfoundation.org, broonie@kernel.org, Bamvor Zhang Jian From: Bamvor Jian Zhang Message-ID: <5683DB05.7000704@linaro.org> Date: Wed, 30 Dec 2015 21:24:21 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.3.0 MIME-Version: 1.0 In-Reply-To: <20151230111648.GA29697@sudip-pc> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, Sudip On 12/30/2015 07:16 PM, Sudip Mukherjee wrote: > On Fri, Dec 18, 2015 at 12:12:05AM +0100, Arnd Bergmann wrote: >> On Thursday 17 December 2015 17:58:52 Bamvor Jian Zhang wrote: >>> The arg of ioctl in ppdev is the pointer of integer except the >>> timeval in PPSETTIME, PPGETTIME. Different size of timeval >>> is already supported by the previous patches. So, it is safe >>> to add compat support. >>> >>> Signed-off-by: Bamvor Jian Zhang >>> >> >> Reviewed-by: Arnd Bergmann >> >> (I think I replied with the reviewed-by tag before to this patch) > > I was testing this series today. And it is breaking my userspace code. I > am attaching my userspace code for you to check. Its very simple > userspace code: > 1: open > 2: ioctl to claim > 3: ioctl - PPGETTIME > 4: ioctl - PPSETTIME > 5: ioctl - PPGETTIME > 6: ioctl - release > 7: close > > Without this series it works as expected. > > With this series applied, the userspace code prints the error message: > PPNEGOT: Bad address > > I traced it with strace and: > ioctl(3, PPGETTIME, 0xbfe91508) = -1 EFAULT (Bad address) Thanks for your testing. It seems that I misuse the parameters. Could you please apply the following patch and try it again? There is no parport in my computer, Thanks. diff --git a/drivers/char/ppdev.c b/drivers/char/ppdev.c index 31bc7b7..9e98d01 100644 --- a/drivers/char/ppdev.c +++ b/drivers/char/ppdev.c @@ -636,7 +636,7 @@ static int pp_do_ioctl(struct file *file, unsigned int cmd, unsigned long arg) if ((time32[0] < 0) || (time32[1] < 0)) return -EINVAL; - if (copy_to_user(time32, argp, sizeof(time32))) + if (copy_to_user(argp, time32, sizeof(time32))) return -EFAULT; return 0; @@ -648,7 +648,7 @@ static int pp_do_ioctl(struct file *file, unsigned int cmd, unsigned long arg) if ((time64[0] < 0) || (time64[1] < 0)) return -EINVAL; - if (copy_to_user(time64, argp, sizeof(time64))) + if (copy_to_user(argp, time64, sizeof(time64))) return -EFAULT; return 0; Regards Bamvor > > regards > sudip >