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=-7.7 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,USER_AGENT_GIT 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 90751C04EBF for ; Tue, 4 Dec 2018 11:26:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 53DC42146D for ; Tue, 4 Dec 2018 11:26:49 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="mLohTg0O" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 53DC42146D Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linuxfoundation.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727284AbeLDL0s (ORCPT ); Tue, 4 Dec 2018 06:26:48 -0500 Received: from mail.kernel.org ([198.145.29.99]:44688 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727166AbeLDK7n (ORCPT ); Tue, 4 Dec 2018 05:59:43 -0500 Received: from localhost (5356596B.cm-6-7b.dynamic.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 691012087F; Tue, 4 Dec 2018 10:59:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1543921181; bh=seDYJtr5bJpUEzg7YnGW6ML+9BhaqsNVTJJDjvRTs/4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=mLohTg0OqFUiAlxg7bpB5lNO4d+7v53Pu/SAoBI2s/S374Ir0szbu7jZFO/e8Alff VnPGDwV5LNZW7LiZZHUPOPSOuAStCTAvBuCf/E/4fAxJJj20b+4/RZNWjSTiSYsvCC 96riwnDKXGbCIW8jR3lKM+d7xrv7naeRFSTao81g= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Qu Wenruo , Filipe Manana , David Sterba Subject: [PATCH 4.19 077/139] Btrfs: fix race between enabling quotas and subvolume creation Date: Tue, 4 Dec 2018 11:49:18 +0100 Message-Id: <20181204103653.312216806@linuxfoundation.org> X-Mailer: git-send-email 2.19.2 In-Reply-To: <20181204103649.950154335@linuxfoundation.org> References: <20181204103649.950154335@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Archived-At: List-Archive: List-Post: 4.19-stable review patch. If anyone has any objections, please let me know. ------------------ From: Filipe Manana commit 552f0329c75b3e1d7f9bb8c9e421d37403f192cd upstream. We have a race between enabling quotas end subvolume creation that cause subvolume creation to fail with -EINVAL, and the following diagram shows how it happens: CPU 0 CPU 1 btrfs_ioctl() btrfs_ioctl_quota_ctl() btrfs_quota_enable() mutex_lock(fs_info->qgroup_ioctl_lock) btrfs_ioctl() create_subvol() btrfs_qgroup_inherit() -> save fs_info->quota_root into quota_root -> stores a NULL value -> tries to lock the mutex qgroup_ioctl_lock -> blocks waiting for the task at CPU0 -> sets BTRFS_FS_QUOTA_ENABLED in fs_info -> sets quota_root in fs_info->quota_root (non-NULL value) mutex_unlock(fs_info->qgroup_ioctl_lock) -> checks quota enabled flag is set -> returns -EINVAL because fs_info->quota_root was NULL before it acquired the mutex qgroup_ioctl_lock -> ioctl returns -EINVAL Returning -EINVAL to user space will be confusing if all the arguments passed to the subvolume creation ioctl were valid. Fix it by grabbing the value from fs_info->quota_root after acquiring the mutex. CC: stable@vger.kernel.org # 4.4+ Reviewed-by: Qu Wenruo Signed-off-by: Filipe Manana Reviewed-by: David Sterba Signed-off-by: David Sterba Signed-off-by: Greg Kroah-Hartman --- fs/btrfs/qgroup.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/fs/btrfs/qgroup.c +++ b/fs/btrfs/qgroup.c @@ -2244,7 +2244,7 @@ int btrfs_qgroup_inherit(struct btrfs_tr int i; u64 *i_qgroups; struct btrfs_fs_info *fs_info = trans->fs_info; - struct btrfs_root *quota_root = fs_info->quota_root; + struct btrfs_root *quota_root; struct btrfs_qgroup *srcgroup; struct btrfs_qgroup *dstgroup; u32 level_size = 0; @@ -2254,6 +2254,7 @@ int btrfs_qgroup_inherit(struct btrfs_tr if (!test_bit(BTRFS_FS_QUOTA_ENABLED, &fs_info->flags)) goto out; + quota_root = fs_info->quota_root; if (!quota_root) { ret = -EINVAL; goto out;