From nobody Wed Sep 3 05:56:33 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id AF7BAFA375A for ; Mon, 24 Oct 2022 12:31:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233849AbiJXMa5 (ORCPT ); Mon, 24 Oct 2022 08:30:57 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60606 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233874AbiJXM2c (ORCPT ); Mon, 24 Oct 2022 08:28:32 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9626486892; Mon, 24 Oct 2022 05:02:13 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 19677B811BB; Mon, 24 Oct 2022 11:58:17 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 73049C433D6; Mon, 24 Oct 2022 11:58:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1666612695; bh=MJMYAYbebJ4eMXZJ9gKN+EzXQUKtgGBJb83mkrtYU5Y=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ENtezN+kAmXuXxsoEKVxxjuIQrRoYkc4RjEtzaiCGMjMxF3shcErEnTGJeWdSVms1 AHcrtdaTR44T7LShFWqVfDkhGTVafJ2lcFQ+98wer3fU7bxZliuRfNXax7eQfgX/2t bONtFofeybvypByUOz+hWrtTaT7GQoR6wGRwq3n0= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Ye Bin , Qu Wenruo , Filipe Manana , David Sterba Subject: [PATCH 4.19 055/229] btrfs: fix race between quota enable and quota rescan ioctl Date: Mon, 24 Oct 2022 13:29:34 +0200 Message-Id: <20221024113000.860747439@linuxfoundation.org> X-Mailer: git-send-email 2.38.1 In-Reply-To: <20221024112959.085534368@linuxfoundation.org> References: <20221024112959.085534368@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Filipe Manana commit 331cd9461412e103d07595a10289de90004ac890 upstream. When enabling quotas, at btrfs_quota_enable(), after committing the transaction, we change fs_info->quota_root to point to the quota root we created and set BTRFS_FS_QUOTA_ENABLED at fs_info->flags. Then we try to start the qgroup rescan worker, first by initializing it with a call to qgroup_rescan_init() - however if that fails we end up freeing the quota root but we leave fs_info->quota_root still pointing to it, this can later result in a use-after-free somewhere else. We have previously set the flags BTRFS_FS_QUOTA_ENABLED and BTRFS_QGROUP_STATUS_FLAG_ON, so we can only fail with -EINPROGRESS at btrfs_quota_enable(), which is possible if someone already called the quota rescan ioctl, and therefore started the rescan worker. So fix this by ignoring an -EINPROGRESS and asserting we can't get any other error. Reported-by: Ye Bin Link: https://lore.kernel.org/linux-btrfs/20220823015931.421355-1-yebin10@h= uawei.com/ CC: stable@vger.kernel.org # 4.19+ Reviewed-by: Qu Wenruo Signed-off-by: Filipe Manana Signed-off-by: David Sterba Signed-off-by: Greg Kroah-Hartman --- fs/btrfs/qgroup.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) --- a/fs/btrfs/qgroup.c +++ b/fs/btrfs/qgroup.c @@ -1035,6 +1035,21 @@ out_add_root: fs_info->qgroup_rescan_running =3D true; btrfs_queue_work(fs_info->qgroup_rescan_workers, &fs_info->qgroup_rescan_work); + } else { + /* + * We have set both BTRFS_FS_QUOTA_ENABLED and + * BTRFS_QGROUP_STATUS_FLAG_ON, so we can only fail with + * -EINPROGRESS. That can happen because someone started the + * rescan worker by calling quota rescan ioctl before we + * attempted to initialize the rescan worker. Failure due to + * quotas disabled in the meanwhile is not possible, because + * we are holding a write lock on fs_info->subvol_sem, which + * is also acquired when disabling quotas. + * Ignore such error, and any other error would need to undo + * everything we did in the transaction we just committed. + */ + ASSERT(ret =3D=3D -EINPROGRESS); + ret =3D 0; } =20 out_free_path: