From patchwork Fri Jan 9 20:36:00 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Omar Sandoval X-Patchwork-Id: 5602671 Return-Path: X-Original-To: patchwork-linux-btrfs@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork1.web.kernel.org (Postfix) with ESMTP id B1C709F357 for ; Fri, 9 Jan 2015 20:36:37 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id DF8D92062D for ; Fri, 9 Jan 2015 20:36:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 01E0420608 for ; Fri, 9 Jan 2015 20:36:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757111AbbAIUgb (ORCPT ); Fri, 9 Jan 2015 15:36:31 -0500 Received: from mail-pd0-f175.google.com ([209.85.192.175]:58578 "EHLO mail-pd0-f175.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754080AbbAIUgQ (ORCPT ); Fri, 9 Jan 2015 15:36:16 -0500 Received: by mail-pd0-f175.google.com with SMTP id g10so19371023pdj.6 for ; Fri, 09 Jan 2015 12:36:16 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:in-reply-to:references; bh=KK1FidZYe9fc5930ehVTgd8oaNjVsCXN0cCOFW210MM=; b=XxcYsLnEDXnLFT1S4Sa9D+LgIEb67e9+zvKfXQP2V5x5TR0jltJ9TkjFpY3O0rBNLs vZPGrjFKsXMGZjBU276ERWnsG9WmRBaP83/4YOG9XSL5uHMN9W683ARziRp/AhLr2G3N UbrM7+UU5M1slgIXMR0AU+3a/k/qAk9zxifNKO2/2bRrwWN3MyggReo4JamII9zu/15M rCl6F1n8z3aYBQ3bDPo0qKNj/eGH0o5fPrTzr05yIiZvtS74boxHpVGSIzUKvNU5cuAb 7ChnPik1zFN3gCVEgnaAVOniZnxDDJGjzJHG5r2rkdcB71LrPd33UIAIb0ifKCPs0M+7 5jKw== X-Gm-Message-State: ALoCoQl9iQU/9oWu8HllN71v5ydM8pEX4BRrPTerLhhLJs2n4Z8ZDCZzCM4UrXse5aCvtrOWXkTN X-Received: by 10.70.64.197 with SMTP id q5mr26096871pds.129.1420835775971; Fri, 09 Jan 2015 12:36:15 -0800 (PST) Received: from mew.dhcp4.washington.edu (D-69-91-187-30.dhcp4.washington.edu. [69.91.187.30]) by mx.google.com with ESMTPSA id k4sm7802089pbq.74.2015.01.09.12.36.14 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Fri, 09 Jan 2015 12:36:15 -0800 (PST) From: Omar Sandoval To: Chris Mason , Josef Bacik , David Sterba , "Paul E. McKenney" , Josh Triplett , Steven Rostedt , Mathieu Desnoyers , Lai Jiangshan , linux-kernel@vger.kernel.org, linux-btrfs@vger.kernel.org Cc: Omar Sandoval Subject: [PATCH RESEND v8 3/3] btrfs: fix suspicious RCU in BTRFS_IOC_DEV_INFO Date: Fri, 9 Jan 2015 12:36:00 -0800 Message-Id: <0c10b4554b91ba49e4b7e2500a17a7961e7ee63e.1420834567.git.osandov@osandov.com> X-Mailer: git-send-email 2.2.1 In-Reply-To: References: In-Reply-To: References: Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, T_RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP A naked read of the value of an RCU pointer isn't safe. Put the whole access in an RCU critical section, not just the pointer dereference. Signed-off-by: Omar Sandoval --- fs/btrfs/ioctl.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c index 7ca1cad..ee2528e 100644 --- a/fs/btrfs/ioctl.c +++ b/fs/btrfs/ioctl.c @@ -2706,6 +2706,7 @@ static long btrfs_ioctl_dev_info(struct btrfs_root *root, void __user *arg) struct btrfs_fs_devices *fs_devices = root->fs_info->fs_devices; int ret = 0; char *s_uuid = NULL; + struct rcu_string *name; di_args = memdup_user(arg, sizeof(*di_args)); if (IS_ERR(di_args)) @@ -2726,17 +2727,16 @@ static long btrfs_ioctl_dev_info(struct btrfs_root *root, void __user *arg) di_args->bytes_used = btrfs_device_get_bytes_used(dev); di_args->total_bytes = btrfs_device_get_total_bytes(dev); memcpy(di_args->uuid, dev->uuid, sizeof(di_args->uuid)); - if (dev->name) { - struct rcu_string *name; - rcu_read_lock(); - name = rcu_dereference(dev->name); + rcu_read_lock(); + name = rcu_dereference(dev->name); + if (name) { strncpy(di_args->path, name->str, sizeof(di_args->path)); - rcu_read_unlock(); di_args->path[sizeof(di_args->path) - 1] = 0; } else { di_args->path[0] = '\0'; } + rcu_read_unlock(); out: mutex_unlock(&fs_devices->device_list_mutex);