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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 7E7EAC433E2 for ; Mon, 18 May 2020 17:41:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5B4C920657 for ; Mon, 18 May 2020 17:41:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1589823674; bh=8JEMHKTX3965n4n18+Ai3xzuSK/PYEZl1GVXvu9fqag=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=jZtfpUhf+uix0FrFdTPpixfpPc1vmKdHCSpO4EMqCCU5JXZZm49FXKN3Vv5b/AxDz xUEVZFRfW4lTvFt2za3/9zApQ0vDlwitsiBhWRfEKy0kx71m6GWoi/Ni46H1QZ8IiJ UJqPuFbPBnXO1IIofyc4RWcTlAyPGBMu3PYeFBGI= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729229AbgERRlN (ORCPT ); Mon, 18 May 2020 13:41:13 -0400 Received: from mail.kernel.org ([198.145.29.99]:36856 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729174AbgERRkx (ORCPT ); Mon, 18 May 2020 13:40:53 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.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 D0BDD20657; Mon, 18 May 2020 17:40:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1589823652; bh=8JEMHKTX3965n4n18+Ai3xzuSK/PYEZl1GVXvu9fqag=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ilCQ/IF27GG8VWgkdSuX6PFcssoGHGQI29XTZyXHKNdYD2OqKwhsl5xj6Cyv79Ka4 SburagasyoOS9/eXl3ga4dBdMNPdFBF+Oz5O6rygz5ULt9du3aiJKGxIEdyXvJYpbY wuzfI96XH97VK3a7NsrZbm4NDCqrMlXDPUP5eQrk= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, syzbot+e73ceacfd8560cc8a3ca@syzkaller.appspotmail.com, syzbot+c2fb6f9ddcea95ba49b5@syzkaller.appspotmail.com, Jarod Wilson , Nikolay Aleksandrov , Josh Poimboeuf , Jann Horn , Jay Vosburgh , Cong Wang , "David S. Miller" Subject: [PATCH 4.4 69/86] net: fix a potential recursive NETDEV_FEAT_CHANGE Date: Mon, 18 May 2020 19:36:40 +0200 Message-Id: <20200518173504.310523547@linuxfoundation.org> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200518173450.254571947@linuxfoundation.org> References: <20200518173450.254571947@linuxfoundation.org> User-Agent: quilt/0.66 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 From: Cong Wang [ Upstream commit dd912306ff008891c82cd9f63e8181e47a9cb2fb ] syzbot managed to trigger a recursive NETDEV_FEAT_CHANGE event between bonding master and slave. I managed to find a reproducer for this: ip li set bond0 up ifenslave bond0 eth0 brctl addbr br0 ethtool -K eth0 lro off brctl addif br0 bond0 ip li set br0 up When a NETDEV_FEAT_CHANGE event is triggered on a bonding slave, it captures this and calls bond_compute_features() to fixup its master's and other slaves' features. However, when syncing with its lower devices by netdev_sync_lower_features() this event is triggered again on slaves when the LRO feature fails to change, so it goes back and forth recursively until the kernel stack is exhausted. Commit 17b85d29e82c intentionally lets __netdev_update_features() return -1 for such a failure case, so we have to just rely on the existing check inside netdev_sync_lower_features() and skip NETDEV_FEAT_CHANGE event only for this specific failure case. Fixes: fd867d51f889 ("net/core: generic support for disabling netdev features down stack") Reported-by: syzbot+e73ceacfd8560cc8a3ca@syzkaller.appspotmail.com Reported-by: syzbot+c2fb6f9ddcea95ba49b5@syzkaller.appspotmail.com Cc: Jarod Wilson Cc: Nikolay Aleksandrov Cc: Josh Poimboeuf Cc: Jann Horn Reviewed-by: Jay Vosburgh Signed-off-by: Cong Wang Acked-by: Nikolay Aleksandrov Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/core/dev.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) --- a/net/core/dev.c +++ b/net/core/dev.c @@ -6449,11 +6449,13 @@ static void netdev_sync_lower_features(s netdev_dbg(upper, "Disabling feature %pNF on lower dev %s.\n", &feature, lower->name); lower->wanted_features &= ~feature; - netdev_update_features(lower); + __netdev_update_features(lower); if (unlikely(lower->features & feature)) netdev_WARN(upper, "failed to disable %pNF on %s!\n", &feature, lower->name); + else + netdev_features_change(lower); } } }