From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755894AbYLaKnH (ORCPT ); Wed, 31 Dec 2008 05:43:07 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753033AbYLaKmx (ORCPT ); Wed, 31 Dec 2008 05:42:53 -0500 Received: from ug-out-1314.google.com ([66.249.92.175]:22645 "EHLO ug-out-1314.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751452AbYLaKmw (ORCPT ); Wed, 31 Dec 2008 05:42:52 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=re:to:from:cc:date:message-id:in-reply-to:references:user-agent :mime-version:content-type:content-transfer-encoding; b=xy7S08ZbDR/YyeDhptyB/Vbe3OY1dHIfPFeyuDWZCcxmx4gswJnGxalUUhStiE2k5i MuYPNBV2IBANllNJsJauKYAUcxlThqoF7itfOQrXdYp36GEFnOIumcgClwdytnF/uga7 /ySjqYmtL0m6r6sTo5PKMjnmQBATEpA+97ypU= Re: [PATCH] Fix sg_io_hdr.info corruption. To: FUJITA Tomonori From: Alexey Zaytsev Cc: James.Bottomley@hansenpartnership.com, Andrew Morton , linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org, jens.axboe@oracle.com Date: Wed, 31 Dec 2008 13:51:43 +0300 Message-ID: <20081231104125.3800.97290.stgit@xl0.local> In-Reply-To: <20081231180759X.fujita.tomonori@lab.ntt.co.jp> References: <20081231180759X.fujita.tomonori@lab.ntt.co.jp> User-Agent: StGit/0.14.3.292.gb975 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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? 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, at worst the user will get it's own garbage insted of the values he left in the fields that the kernel was supposed to set. If so, please could 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) {