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=-10.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 F3C5BC04EBF for ; Wed, 5 Dec 2018 09:50:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B9B7B214C1 for ; Wed, 5 Dec 2018 09:50:00 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="tF+R+Eqh" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B9B7B214C1 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.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 S1729616AbeLEJt7 (ORCPT ); Wed, 5 Dec 2018 04:49:59 -0500 Received: from mail.kernel.org ([198.145.29.99]:56184 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728452AbeLEJt5 (ORCPT ); Wed, 5 Dec 2018 04:49:57 -0500 Received: from sasha-vm.mshome.net (unknown [213.57.143.11]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 0F9792133F; Wed, 5 Dec 2018 09:49:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1544003397; bh=Z0XsMpCBym0QwU9vaxF3AqZe6uSNiCLBFAbPIz2vv1E=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=tF+R+Eqhu5mZ7cTpuKFOAjMx58+BXV7dRXlKfkNbQZmxw/RkI1mVtq6Fn+JNIbjcv t/tYkxTSDwYnlej7cnMi8vSaSBdrlWrJkMUD0m8c54530F+5pk4x2GvfI54FjGqePs YF/rIVX09/1uMyVzdAxpj4T1TYtfTIQu0BCzKjN4= From: Sasha Levin To: stable@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Pan Bian , Al Viro , Sasha Levin Subject: [PATCH AUTOSEL 4.9 19/45] exportfs: do not read dentry after free Date: Wed, 5 Dec 2018 04:46:40 -0500 Message-Id: <20181205094706.7225-19-sashal@kernel.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20181205094706.7225-1-sashal@kernel.org> References: <20181205094706.7225-1-sashal@kernel.org> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Pan Bian [ 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; } -- 2.17.1