From mboxrd@z Thu Jan 1 00:00:00 1970 From: Douglas Gilbert Subject: Re: [PATCH] Fix sg_io_hdr.info corruption. Date: Thu, 01 Jan 2009 09:54:00 -0500 Message-ID: <495CD908.6050700@interlog.com> References: <20081231180759X.fujita.tomonori@lab.ntt.co.jp> <20090101110133.14065.98145.stgit@zaytsev.su> Reply-To: dgilbert@interlog.com Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from smtp.infotech.no ([82.134.31.41]:33807 "EHLO elrond2.infotech.no" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756009AbZAAOyK (ORCPT ); Thu, 1 Jan 2009 09:54:10 -0500 In-Reply-To: <20090101110133.14065.98145.stgit@zaytsev.su> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Alexey Zaytsev Cc: FUJITA Tomonori , James.Bottomley@hansenpartnership.com, Andrew Morton , linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org, jens.axboe@oracle.com Alexey Zaytsev wrote: > [resending in case you missed the one I sent with broken headers] > > On Wed, Dec 31, 2008 at 12:08, FUJITA Tomonori wrote: >> On Tue, 30 Dec 2008 15:46:03 -0800 >> Andrew Morton wrote: > [...] >>> the code has been like this for years and years. Why hasn't anyone >>> noticed? >> The members from 'status' in struct sg_io_hdr to the last are used to >> transfer information from kernel to user space. The values that user >> space sets are just ignored. >> > > Then probably there is no need to copy those fields, right? Correct. Doug Gilbert > There should be no data leak from the kernel, as sgio is > allocated on the userspace stack, and the appropriate ioctl > handler should set/zero all those fields anyway, as it expects > them to come directly from the user (did not check). > So, in the worst case the user gets his own garbage insted of > the values he left in the fields that the kernel was supposed > to set. > > If so, please drop my previous patch and take this one. > > From: Alexey Zaytsev > Subject: [PATCH] Don't perform unneeded copy. > > FUJITA Tomonori says: > > The members from 'status' in struct sg_io_hdr to the last are used to > transfer information from kernel to user space. The values that user > space sets are just ignored. > > Signed-off-by: Alexey Zaytsev > --- > fs/compat_ioctl.c | 6 ------ > 1 files changed, 0 insertions(+), 6 deletions(-) > > diff --git a/fs/compat_ioctl.c b/fs/compat_ioctl.c > index 5235c67..23b1f5a 100644 > --- a/fs/compat_ioctl.c > +++ b/fs/compat_ioctl.c > @@ -782,12 +782,6 @@ static int sg_ioctl_trans(unsigned int fd, unsigned int cmd, unsigned long arg) > if (put_user(compat_ptr(data), &sgio->usr_ptr)) > return -EFAULT; > > - if (copy_in_user(&sgio->status, &sgio32->status, > - (4 * sizeof(unsigned char)) + > - (2 * sizeof(unsigned (short))) + > - (3 * sizeof(int)))) > - return -EFAULT; > - > err = sys_ioctl(fd, cmd, (unsigned long) sgio); > > if (err >= 0) { > > -- > To unsubscribe from this list: send the line "unsubscribe linux-scsi" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >