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 84253C433F5 for ; Fri, 4 Feb 2022 09:21:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1357414AbiBDJVK (ORCPT ); Fri, 4 Feb 2022 04:21:10 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60458 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1357328AbiBDJU4 (ORCPT ); Fri, 4 Feb 2022 04:20:56 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2477CC06173D; Fri, 4 Feb 2022 01:20:56 -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 dfw.source.kernel.org (Postfix) with ESMTPS id A5EB8615F4; Fri, 4 Feb 2022 09:20:55 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0B019C004E1; Fri, 4 Feb 2022 09:20:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1643966455; bh=Buyr2y4TEqLxbZmnYSPF0uitMkHzi9EYfbtbFaPM5As=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=zc2asGB4NPIpzDr3ShJthHwBGDpaQ0ACGBzxl5pg59IYkFmSK+HQ+M4iX4wv2NrhB E3qS83WhyC7sTfWSTnJTbSbLPmt540bP1F6bCPOUE0h8auuRtI7Oh3hjvAQVBvKfd4 XoLIugsBAG62mcaLT0m/RjCj+tTdsfTlOXWr7DpM= 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 5.4 08/10] rtnetlink: make sure to refresh master_dev/m_ops in __rtnl_newlink() Date: Fri, 4 Feb 2022 10:20:21 +0100 Message-Id: <20220204091912.593539145@linuxfoundation.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220204091912.329106021@linuxfoundation.org> References: <20220204091912.329106021@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 @@ -3022,8 +3022,8 @@ static int __rtnl_newlink(struct sk_buff struct nlattr *slave_attr[RTNL_SLAVE_MAX_TYPE + 1]; unsigned char name_assign_type = NET_NAME_USER; struct nlattr *linkinfo[IFLA_INFO_MAX + 1]; - const struct rtnl_link_ops *m_ops = NULL; - struct net_device *master_dev = NULL; + const struct rtnl_link_ops *m_ops; + struct net_device *master_dev; struct net *net = sock_net(skb->sk); const struct rtnl_link_ops *ops; struct nlattr *tb[IFLA_MAX + 1]; @@ -3063,6 +3063,8 @@ replay: dev = NULL; } + master_dev = NULL; + m_ops = NULL; if (dev) { master_dev = netdev_master_upper_dev_get(dev); if (master_dev)