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 4E91AC433E0 for ; Mon, 18 May 2020 18:01:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2DC1720826 for ; Mon, 18 May 2020 18:01:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1589824871; bh=1aBEUp+/e3gYMptFBPvb8F4b1qs5iocbB6uHnnswR5k=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=Ei94TnkT6A5WrEsyHyuLnM1RlzcgMEjzVCMO4wmnvNtABsNziGyNVgZMRV/GlRsjb MIQwjKZFDeaYKWCO9oK6AMuBWCGBlo77z80HcHYNTN32RplWoJOki0oABJc1RNWNJ4 oJ4l+mcfW4K335KO6CqFWJnDG1VcoOFysz+d3q8o= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732366AbgERSBK (ORCPT ); Mon, 18 May 2020 14:01:10 -0400 Received: from mail.kernel.org ([198.145.29.99]:43024 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731516AbgERSBC (ORCPT ); Mon, 18 May 2020 14:01:02 -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 59B1820826; Mon, 18 May 2020 18:01:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1589824861; bh=1aBEUp+/e3gYMptFBPvb8F4b1qs5iocbB6uHnnswR5k=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Ic/vSbgdXHgOqT8G4lnmYEFFhK63qAzgxg3kS7d61PlIZLBiOWkZIqlVAL2EOeHIU TrKNwQTx+jxKNe5sw9ORXjd6iNSSBrUa5zGlM3ftgwuWYjx6O++QGlcQA737bfRgl+ A0uLshvafsT0EPtFuH54izuE9GKPsMxNB43I1r94= 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 5.6 032/194] net: fix a potential recursive NETDEV_FEAT_CHANGE Date: Mon, 18 May 2020 19:35:22 +0200 Message-Id: <20200518173534.232518410@linuxfoundation.org> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200518173531.455604187@linuxfoundation.org> References: <20200518173531.455604187@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 @@ -8890,11 +8890,13 @@ 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); } } }