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=-9.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED,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 7B8E9C6786C for ; Fri, 14 Dec 2018 12:25:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 434C02080F for ; Fri, 14 Dec 2018 12:25:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1544790348; bh=BjX0dgq1/iREoFjAtcR2RH70gn2C5UICXJgp43/uSOQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=H/FRwEZZdsxBDnyC8VBoqW0I+uKFnL3Na4KF2QZfeyP3itaTDvALX5iDGdx+2lze7 wSa/BIVQXER0AcpYCq+muTMWtHxGfDk59WH94e12O//St3GwYhKD9xilQxrfsEYi3X Vt1r9CynqnptanwirySU3Hh4NuCzHcGp/63VKqsw= DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 434C02080F 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 S1731894AbeLNMMN (ORCPT ); Fri, 14 Dec 2018 07:12:13 -0500 Received: from mail.kernel.org ([198.145.29.99]:59130 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731885AbeLNMMG (ORCPT ); Fri, 14 Dec 2018 07:12:06 -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 52798214D9; Fri, 14 Dec 2018 12:12:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1544789525; bh=BjX0dgq1/iREoFjAtcR2RH70gn2C5UICXJgp43/uSOQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=MplccDDlm3I+IX/PLXs10k1IG4JqG5xd9Vkwyq3hJ5ZWIdEjaEDJMWskMFa4p5s7W HodSzEWS4KS+lqsW1fxvdZcPpY7sNB1yGlcxtMlWJm1rrCdeAh3hTCiTlrP9FmCqvp j8XKvyaKlZSwsciDzN2rK9c/KFjsiMkYfhTljius= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Pan Bian , Al Viro , Sasha Levin Subject: [PATCH 4.9 27/51] exportfs: do not read dentry after free Date: Fri, 14 Dec 2018 13:00:29 +0100 Message-Id: <20181214115715.773029553@linuxfoundation.org> X-Mailer: git-send-email 2.20.0 In-Reply-To: <20181214115713.244259772@linuxfoundation.org> References: <20181214115713.244259772@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 4.9-stable review patch. If anyone has any objections, please let me know. ------------------ [ Upstream commit 2084ac6c505a58f7efdec13eba633c6aaa085ca5 ] The function dentry_connected calls dput(dentry) to drop the previously acquired reference to dentry. In this case, dentry can be released. After that, IS_ROOT(dentry) checks the condition (dentry == dentry->d_parent), which may result in a use-after-free bug. This patch directly compares dentry with its parent obtained before dropping the reference. Fixes: a056cc8934c("exportfs: stop retrying once we race with rename/remove") Signed-off-by: Pan Bian Signed-off-by: Al Viro Signed-off-by: Sasha Levin --- fs/exportfs/expfs.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/exportfs/expfs.c b/fs/exportfs/expfs.c index a4b531be9168..7a7bba7c2328 100644 --- a/fs/exportfs/expfs.c +++ b/fs/exportfs/expfs.c @@ -76,7 +76,7 @@ static bool dentry_connected(struct dentry *dentry) struct dentry *parent = dget_parent(dentry); dput(dentry); - if (IS_ROOT(dentry)) { + if (dentry == parent) { dput(parent); return false; } -- 2.19.1