From patchwork Tue Apr 30 03:25:24 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Darrick J. Wong" X-Patchwork-Id: 13648007 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7883F10A01; Tue, 30 Apr 2024 03:25:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1714447525; cv=none; b=iUkL9ecsWC9Ys4n0m3OsekPlW7/OZHXzhWxslxDpzbJptbdsPjNKjVL184koEJ4va9UZlP62B6TJYTxujKXtVY6UyN/eh8sFpQT3SX05Zou5KC9qPskvhsQs5Tamnr4z4ngTTMZ5mhX3aRRpLNCvrkyE+R7uM+A3U1mJxWR2GzA= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1714447525; c=relaxed/simple; bh=6ObMVCZ176J4MGZvZ9Xo+UTcnuFTDMOn8PD7QGqsiVc=; h=Date:Subject:From:To:Cc:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=DDp88B3GsFfscHSIqhbnYEiSXwag2Xto3LPMZ2UPgxd56TNFkINht/35LBaHLZHO1jnoGjoXS+TIJUYnKX/ImO5fsQ1bSYPL+nn9EIPbYYrAZOMuAI9vpEfKjrg4xkTo8eVGbrfMpA6SKF4gjB8wMVaTIdx3xOQ293ZVnOmIBis= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Eo3Eitqa; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Eo3Eitqa" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 043F3C116B1; Tue, 30 Apr 2024 03:25:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1714447525; bh=6ObMVCZ176J4MGZvZ9Xo+UTcnuFTDMOn8PD7QGqsiVc=; h=Date:Subject:From:To:Cc:In-Reply-To:References:From; b=Eo3EitqaDX6sS15nAIvCwlNJ3kSnugQuW+7nMJlASRpwcg5ojPNX3YXRgFOcLc9yL PX4KDjRUdlpKkZzfRQr3u7mjSNtXN+bd5nx6MTkIOEWywUbVB12jKkOQ0qSTvxztTo Lnt13/saL9/4xBIslbD0m9oEnIQFL4S1PPVwIdjZdECO7mzSFFmJnXyjvbn/YGgp4h 0SPt++vRyWlqk/QTKNNEDSX0mVCcGRzLfomKFmSUVqfmVHNMcTKKwW5g7OO0uRJk2M SaJqthugaY1mcuFcvsIWeDNMgInI+WSTeYd4aLMYWlzD6Z1ItdkCSPELEp5EyAFcpp n7J8WK+gLfFYA== Date: Mon, 29 Apr 2024 20:25:24 -0700 Subject: [PATCH 05/26] xfs: use an empty transaction to protect xfs_attr_get from deadlocks From: "Darrick J. Wong" To: aalbersh@redhat.com, ebiggers@kernel.org, djwong@kernel.org Cc: linux-xfs@vger.kernel.org, alexl@redhat.com, walters@verbum.org, fsverity@lists.linux.dev, linux-fsdevel@vger.kernel.org Message-ID: <171444680446.957659.9938547111608933605.stgit@frogsfrogsfrogs> In-Reply-To: <171444680291.957659.15782417454902691461.stgit@frogsfrogsfrogs> References: <171444680291.957659.15782417454902691461.stgit@frogsfrogsfrogs> User-Agent: StGit/0.19 Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 From: Darrick J. Wong Wrap the xfs_attr_get_ilocked call in xfs_attr_get with an empty transaction so that we cannot livelock the kernel if someone injects a loop into the attr structure or the attr fork bmbt. Signed-off-by: Darrick J. Wong --- fs/xfs/libxfs/xfs_attr.c | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c index b841096947acb..e0be8d0c1ffdc 100644 --- a/fs/xfs/libxfs/xfs_attr.c +++ b/fs/xfs/libxfs/xfs_attr.c @@ -274,6 +274,8 @@ xfs_attr_get( XFS_STATS_INC(args->dp->i_mount, xs_attr_get); + ASSERT(!args->trans); + if (xfs_is_shutdown(args->dp->i_mount)) return -EIO; @@ -286,8 +288,27 @@ xfs_attr_get( /* Entirely possible to look up a name which doesn't exist */ args->op_flags = XFS_DA_OP_OKNOENT; + error = xfs_trans_alloc_empty(args->dp->i_mount, &args->trans); + if (error) + return error; + lock_mode = xfs_ilock_attr_map_shared(args->dp); + + /* + * Make sure the attr fork iext tree is loaded. Use the empty + * transaction to load the bmbt so that we avoid livelocking on loops. + */ + if (xfs_inode_hasattr(args->dp)) { + error = xfs_iread_extents(args->trans, args->dp, XFS_ATTR_FORK); + if (error) + goto out_cancel; + } + error = xfs_attr_get_ilocked(args); + +out_cancel: + xfs_trans_cancel(args->trans); + args->trans = NULL; xfs_iunlock(args->dp, lock_mode); return error;