From patchwork Wed Aug 23 06:46:03 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Omar Sandoval X-Patchwork-Id: 9916695 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id D1836600C5 for ; Wed, 23 Aug 2017 06:46:25 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id C3F6F23201 for ; Wed, 23 Aug 2017 06:46:25 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id B912828628; Wed, 23 Aug 2017 06:46:25 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=2.0 tests=BAYES_00,DKIM_SIGNED, RCVD_IN_DNSWL_HI,T_DKIM_INVALID autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 66EA72858A for ; Wed, 23 Aug 2017 06:46:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753406AbdHWGqV (ORCPT ); Wed, 23 Aug 2017 02:46:21 -0400 Received: from mail-pg0-f54.google.com ([74.125.83.54]:34456 "EHLO mail-pg0-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753057AbdHWGqS (ORCPT ); Wed, 23 Aug 2017 02:46:18 -0400 Received: by mail-pg0-f54.google.com with SMTP id s14so4042209pgs.1 for ; Tue, 22 Aug 2017 23:46:17 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=osandov-com.20150623.gappssmtp.com; s=20150623; h=from:to:cc:subject:date:message-id:in-reply-to:references :in-reply-to:references; bh=S7zVLtzi23W9nHzqecREuDV4PmE7uRAyu8BxHgtVrtY=; b=F4GjPfYujTipukTY52s8Jm5XPFrvnSfDep3PtJ7mMRgmXd+B9BrgkaUa4n89lf2xeU fawVuHzowZe2x1OgkP2RMNtbLLEuFhUSznstNngdXCPDrh2r2ZE0K4uoz32KeT/pA4VC XFkAf4r9FpeJ5epx0orBwwHNs5n7QSjDQL3w1TgEOSEHMO8dtbIwsqwlkQgNUJpuGDkZ kf0I4aqgMRbsCet1Zzk1sRa/UxBTbEV5ZVkKVaUtUz6tk1kvaj5T7wtYxqnJ8TBao4f6 PMRCEKtmFmr7I25dw3ylIaIUJGOGR/Y3HN1BtKezKeQYYWcciWLgf6wcnyAkn6aeBBRe sBGw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:in-reply-to:references; bh=S7zVLtzi23W9nHzqecREuDV4PmE7uRAyu8BxHgtVrtY=; b=NJZA72+8U4QFdU/aF0ATbxyDo5vhoRC95CexOPgrYb2okR10A+FG9EOqdcg7wxjkZA Gp2q0p4Xbxis5hShy5kPSyokb8mBmtJB4vlwAf9WaFuWg2iWmaOmF6vJK074aqAngElR o58/laaKsIQazclGuj3HH9FZVESZkyfSwL0jK8iJd9B8Ea3C/MIiEOCSCFogSrC0/TSW tQNYOjsIwloV815SUgERlleJgYHcTvZ0gUQ15m575CUipABE4I1AAB9QsIkQgjdYJkX3 M8zHYU3bUZrDQ7BlImZBfol5CVSL/IbP28rlUsqXZNps2EYMuThsAPlxZF+eIyLntJ+C WbBA== X-Gm-Message-State: AHYfb5iaSgJjg+7C7NlYDqf6/S7gQul20mdm8hiV3SIdemzuN1Erw1uD X5SBbrbzqBjm+S8Bg2Utww== X-Received: by 10.99.96.149 with SMTP id u143mr1745780pgb.348.1503470777057; Tue, 22 Aug 2017 23:46:17 -0700 (PDT) Received: from localhost.localdomain ([2601:602:8801:8110:e6a7:a0ff:fe0b:c9a8]) by smtp.gmail.com with ESMTPSA id n184sm1194749pga.89.2017.08.22.23.46.16 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 22 Aug 2017 23:46:16 -0700 (PDT) From: Omar Sandoval To: linux-btrfs@vger.kernel.org Cc: kernel-team@fb.com Subject: [PATCH 5/7] Btrfs: fix suspicious RCU in BTRFS_IOC_DEV_INFO Date: Tue, 22 Aug 2017 23:46:03 -0700 Message-Id: <433d5c3c5a47154a8bead243a9f6e0c8b3b7ad7d.1503470354.git.osandov@fb.com> X-Mailer: git-send-email 2.14.1 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-Virus-Scanned: ClamAV using ClamSMTP From: Omar Sandoval 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 befeacd0e847..cf71d0304671 100644 --- a/fs/btrfs/ioctl.c +++ b/fs/btrfs/ioctl.c @@ -2823,6 +2823,7 @@ static long btrfs_ioctl_dev_info(struct btrfs_fs_info *fs_info, struct btrfs_fs_devices *fs_devices = 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)) @@ -2843,17 +2844,16 @@ static long btrfs_ioctl_dev_info(struct btrfs_fs_info *fs_info, 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);