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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5E384CCA47B for ; Mon, 13 Jun 2022 10:56:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1348573AbiFMK4W (ORCPT ); Mon, 13 Jun 2022 06:56:22 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44046 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1348769AbiFMKyA (ORCPT ); Mon, 13 Jun 2022 06:54:00 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CB7752ED6C; Mon, 13 Jun 2022 03:27:50 -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 dfw.source.kernel.org (Postfix) with ESMTPS id 5C90F60ED7; Mon, 13 Jun 2022 10:27:50 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 71057C3411E; Mon, 13 Jun 2022 10:27:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1655116069; bh=MH+jVAq6gHql77W/E2asVonBTzuDrvB/pKfbqPiaEQ8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=eWf9LHGrShST8q1nrLZqczSzi+JILhEOIQ26rDRCTjgGPB1OsXDLGTbShoGsJWJuE tFw4HBotT41FzgBeLnTlow7Rv3IvZGaC9//iRhpdN+ukB8coyeu52nMGQx+livQ757 5Ig7EsC+jhbEDWdfNLGvhSjB1f4uVU2osUp4Xm5Y= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Guoqing Jiang , Xiaomeng Tong , Goldwyn Rodrigues , Song Liu Subject: [PATCH 4.14 117/218] md: fix an incorrect NULL check in does_sb_need_changing Date: Mon, 13 Jun 2022 12:09:35 +0200 Message-Id: <20220613094924.117838903@linuxfoundation.org> X-Mailer: git-send-email 2.36.1 In-Reply-To: <20220613094908.257446132@linuxfoundation.org> References: <20220613094908.257446132@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Xiaomeng Tong commit fc8738343eefc4ea8afb6122826dea48eacde514 upstream. The bug is here: if (!rdev) The list iterator value 'rdev' will *always* be set and non-NULL by rdev_for_each(), so it is incorrect to assume that the iterator value will be NULL if the list is empty or no element found. Otherwise it will bypass the NULL check and lead to invalid memory access passing the check. To fix the bug, use a new variable 'iter' as the list iterator, while using the original variable 'rdev' as a dedicated pointer to point to the found element. Cc: stable@vger.kernel.org Fixes: 2aa82191ac36 ("md-cluster: Perform a lazy update") Acked-by: Guoqing Jiang Signed-off-by: Xiaomeng Tong Acked-by: Goldwyn Rodrigues Signed-off-by: Song Liu Signed-off-by: Greg Kroah-Hartman --- drivers/md/md.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -2427,14 +2427,16 @@ static void sync_sbs(struct mddev *mddev static bool does_sb_need_changing(struct mddev *mddev) { - struct md_rdev *rdev; + struct md_rdev *rdev = NULL, *iter; struct mdp_superblock_1 *sb; int role; /* Find a good rdev */ - rdev_for_each(rdev, mddev) - if ((rdev->raid_disk >= 0) && !test_bit(Faulty, &rdev->flags)) + rdev_for_each(iter, mddev) + if ((iter->raid_disk >= 0) && !test_bit(Faulty, &iter->flags)) { + rdev = iter; break; + } /* No good device found. */ if (!rdev)