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 AD216C46467 for ; Mon, 7 Feb 2022 11:19:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1378798AbiBGLP4 (ORCPT ); Mon, 7 Feb 2022 06:15:56 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49722 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1354429AbiBGLMV (ORCPT ); Mon, 7 Feb 2022 06:12:21 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D19FEC043181; Mon, 7 Feb 2022 03:12:20 -0800 (PST) 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 ams.source.kernel.org (Postfix) with ESMTPS id 8D0A4B81028; Mon, 7 Feb 2022 11:12:19 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id A4498C340EB; Mon, 7 Feb 2022 11:12:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1644232338; bh=AYafRmXmyRXCNqMdkz7flGgefQH/FAXI5WkNagMnnZQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=VsSazAiFSty20+didcZyvDfYVOYld+PhkE6OKGOdaEXM/mmNxawsnAjQLlh1I+suu p7nR7iLYHhjqXLgSAexmJDellN6UEPEk8BDI87Dl1Fq+OBGS37+T23oXVU9LvK7UbT 1Lvb9vRerhmitT5bf+RuLsWmmIlwWANsjN5H3Vss= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Eric Dumazet , Jiri Pirko , Jakub Kicinski Subject: [PATCH 4.14 44/69] rtnetlink: make sure to refresh master_dev/m_ops in __rtnl_newlink() Date: Mon, 7 Feb 2022 12:06:06 +0100 Message-Id: <20220207103757.078634102@linuxfoundation.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220207103755.604121441@linuxfoundation.org> References: <20220207103755.604121441@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: Eric Dumazet commit c6f6f2444bdbe0079e41914a35081530d0409963 upstream. While looking at one unrelated syzbot bug, I found the replay logic in __rtnl_newlink() to potentially trigger use-after-free. It is better to clear master_dev and m_ops inside the loop, in case we have to replay it. Fixes: ba7d49b1f0f8 ("rtnetlink: provide api for getting and setting slave info") Signed-off-by: Eric Dumazet Cc: Jiri Pirko Link: https://lore.kernel.org/r/20220201012106.216495-1-eric.dumazet@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- net/core/rtnetlink.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) --- a/net/core/rtnetlink.c +++ b/net/core/rtnetlink.c @@ -2523,9 +2523,9 @@ static int rtnl_newlink(struct sk_buff * { struct net *net = sock_net(skb->sk); const struct rtnl_link_ops *ops; - const struct rtnl_link_ops *m_ops = NULL; + const struct rtnl_link_ops *m_ops; struct net_device *dev; - struct net_device *master_dev = NULL; + struct net_device *master_dev; struct ifinfomsg *ifm; char kind[MODULE_NAME_LEN]; char ifname[IFNAMSIZ]; @@ -2556,6 +2556,8 @@ replay: dev = NULL; } + master_dev = NULL; + m_ops = NULL; if (dev) { master_dev = netdev_master_upper_dev_get(dev); if (master_dev)