From patchwork Tue Mar 10 12:38:50 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 229461 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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT autolearn=unavailable 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 D2A1AC10F27 for ; Tue, 10 Mar 2020 13:35:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9D85D20675 for ; Tue, 10 Mar 2020 13:35:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1583847304; bh=+cAswMxICauY55nftB9OIrbu+ADdoLTyXUMn+AqHzDc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=UKl2L/dOv2sIzB2aBrj/U5xGbjZqbMQWU6FHfNQxB0AtzoGN311NXrQaqZvx0RfLL guqLPkSx/KaArJnVTpEMFDoSjj+uSUpXlGAgGCSLuylpzAkZ1QQv2N/j7slQENi9yk d5dAm7whapqAtIhE0naUp5si5njxG6ibNjIbH+SQ= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727922AbgCJMpa (ORCPT ); Tue, 10 Mar 2020 08:45:30 -0400 Received: from mail.kernel.org ([198.145.29.99]:48130 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727559AbgCJMp3 (ORCPT ); Tue, 10 Mar 2020 08:45:29 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.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 2227A246A2; Tue, 10 Mar 2020 12:45:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1583844328; bh=+cAswMxICauY55nftB9OIrbu+ADdoLTyXUMn+AqHzDc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Msfsk2f7E3DvBE5IJ0AbBRHBmviI/nt4g/qM6BWJXA/OoWf57ImnEIpOaKRF8zYiF LJW5UyeVAkuj4uzZeFpAyNAQMOFgf81d+ex34MVWxJsDqUnp9/7SmeXbLsrM6AvDUd nBKKqFS7caJRJ0faSzXenI/potrZ2otAtl5feOnI= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, "Eric W. Biederman" , Al Viro , Aleksa Sarai Subject: [PATCH 4.9 42/88] namei: only return -ECHILD from follow_dotdot_rcu() Date: Tue, 10 Mar 2020 13:38:50 +0100 Message-Id: <20200310123616.295697790@linuxfoundation.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200310123606.543939933@linuxfoundation.org> References: <20200310123606.543939933@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Aleksa Sarai commit 2b98149c2377bff12be5dd3ce02ae0506e2dd613 upstream. It's over-zealous to return hard errors under RCU-walk here, given that a REF-walk will be triggered for all other cases handling ".." under RCU. The original purpose of this check was to ensure that if a rename occurs such that a directory is moved outside of the bind-mount which the resolution started in, it would be detected and blocked to avoid being able to mess with paths outside of the bind-mount. However, triggering a new REF-walk is just as effective a solution. Cc: "Eric W. Biederman" Fixes: 397d425dc26d ("vfs: Test for and handle paths that are unreachable from their mnt_root") Suggested-by: Al Viro Signed-off-by: Aleksa Sarai Signed-off-by: Al Viro Signed-off-by: Greg Kroah-Hartman --- fs/namei.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/fs/namei.c +++ b/fs/namei.c @@ -1370,7 +1370,7 @@ static int follow_dotdot_rcu(struct name nd->path.dentry = parent; nd->seq = seq; if (unlikely(!path_connected(&nd->path))) - return -ENOENT; + return -ECHILD; break; } else { struct mount *mnt = real_mount(nd->path.mnt);