From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.2 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id DB643C43387 for ; Mon, 17 Dec 2018 08:25:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A9E6420672 for ; Mon, 17 Dec 2018 08:25:38 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="ctpccwdr" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731770AbeLQIZh (ORCPT ); Mon, 17 Dec 2018 03:25:37 -0500 Received: from userp2130.oracle.com ([156.151.31.86]:45238 "EHLO userp2130.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731707AbeLQIZh (ORCPT ); Mon, 17 Dec 2018 03:25:37 -0500 Received: from pps.filterd (userp2130.oracle.com [127.0.0.1]) by userp2130.oracle.com (8.16.0.22/8.16.0.22) with SMTP id wBH8OC7B014476; Mon, 17 Dec 2018 08:25:35 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=subject : to : references : from : cc : message-id : date : mime-version : in-reply-to : content-type : content-transfer-encoding; s=corp-2018-07-02; bh=5bKtgLyAvjipL9fWWz9jjwoQdqYlCIbvfJjIWcU33Uc=; b=ctpccwdrOdWdx1s4DNpJ+wMpW+QZW8QBKrdqKpVf0Hu5cTRHpxGYDlF95CY1VLg3Q/wk w5J9IKEJisM16LyR4IKBZelz2DHqeom2geCHBsVTF9SC+n7PKG7+vFJZeYzI79o12DDj Cw1Z+M8x2tUzEV2yvyzibwoy3rk7X333HO106octoYlTQpQnifqY8bfouL1IJNRq6kY3 HpKt1rA0g3OpDn4gJkJCEfRSDG/9Jm4q2PZp0spimsAaGUB2K/DUo1uC7XXb8vMujLXE 7rDj1grTTvstypq65D8zC1JiWxfFbfUUS5CvK+uzpAwp9CHzMzjiy0PG+QvlfBPpuHVD zg== Received: from userv0022.oracle.com (userv0022.oracle.com [156.151.31.74]) by userp2130.oracle.com with ESMTP id 2pcs1tcdb5-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 17 Dec 2018 08:25:35 +0000 Received: from userv0121.oracle.com (userv0121.oracle.com [156.151.31.72]) by userv0022.oracle.com (8.14.4/8.14.4) with ESMTP id wBH8PTQ0027031 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 17 Dec 2018 08:25:29 GMT Received: from abhmp0020.oracle.com (abhmp0020.oracle.com [141.146.116.26]) by userv0121.oracle.com (8.14.4/8.13.8) with ESMTP id wBH8PT9o011574; Mon, 17 Dec 2018 08:25:29 GMT Received: from [172.20.10.2] (/157.49.131.71) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Mon, 17 Dec 2018 00:25:29 -0800 Subject: Re: [PATCH] Btrfs: do not overwrite error return value in the balance ioctl To: fdmanana@kernel.org References: <20181214194541.21891-1-fdmanana@kernel.org> From: Anand Jain Cc: linux-btrfs@vger.kernel.org Message-ID: <9c378108-591d-e275-8898-3c67d97156fa@oracle.com> Date: Mon, 17 Dec 2018 16:25:35 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20181214194541.21891-1-fdmanana@kernel.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=9109 signatures=668679 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=1 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1812170080 Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On 12/15/2018 03:45 AM, fdmanana@kernel.org wrote: > From: Filipe Manana > > If the call to btrfs_balance() failed we would overwrite the error > returned to user space with -EFAULT if the call to copy_to_user() failed > as well. Fix that by calling copy_to_user() only if btrfs_balance() > returned success. > > Signed-off-by: Filipe Manana > --- > fs/btrfs/ioctl.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c > index abe45fd97ab5..4ad7288f77d0 100644 > --- a/fs/btrfs/ioctl.c > +++ b/fs/btrfs/ioctl.c > @@ -4707,7 +4707,7 @@ static long btrfs_ioctl_balance(struct file *file, void __user *arg) > ret = btrfs_balance(fs_info, bctl, bargs); > bctl = NULL; > > - if (arg) { > + if (ret == 0 && arg) { > if (copy_to_user(arg, bargs, sizeof(*bargs))) > ret = -EFAULT; > } > This changes the BTRFS_IOC_BALANCE_V2 semantics. Originally, if BTRFS_IOC_BALANCE_V2 is failed/canceled we do update bargs [1] and copy to user land, but after this patch we copy only if the ioctl is successful. I doubt if David is OK with that. [1] ---------- 3717 int btrfs_balance(struct btrfs_fs_info *fs_info, 3718 struct btrfs_balance_control *bctl, 3719 struct btrfs_ioctl_balance_args *bargs) 3720 { :: 3855 ret = __btrfs_balance(fs_info); 3856 3857 mutex_lock(&fs_info->balance_mutex); 3858 clear_bit(BTRFS_FS_BALANCE_RUNNING, &fs_info->flags); 3859 3860 if (bargs) { 3861 memset(bargs, 0, sizeof(*bargs)); 3862 btrfs_update_ioctl_balance_args(fs_info, bargs); 3863 }