From patchwork Tue Apr 22 04:17:50 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Gibson X-Patchwork-Id: 341173 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 496161400F9 for ; Tue, 22 Apr 2014 14:17:59 +1000 (EST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751234AbaDVERz (ORCPT ); Tue, 22 Apr 2014 00:17:55 -0400 Received: from mx1.redhat.com ([209.132.183.28]:22555 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750716AbaDVERy (ORCPT ); Tue, 22 Apr 2014 00:17:54 -0400 Received: from int-mx11.intmail.prod.int.phx2.redhat.com (int-mx11.intmail.prod.int.phx2.redhat.com [10.5.11.24]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id s3M4Hqjs004982 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 22 Apr 2014 00:17:53 -0400 Received: from voom (vpn1-48-38.bne.redhat.com [10.64.48.38]) by int-mx11.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id s3M4Hm3A026871 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Tue, 22 Apr 2014 00:17:50 -0400 Date: Tue, 22 Apr 2014 14:17:50 +1000 From: David Gibson To: David Gibson Cc: netdev@vger.kernel.org, Christian Benvenuti , Sujith Sankar , Govindarajulu Varadarajan , Neel Patel , Nishank Trivedi Subject: Re: RFC: rtnetlink problems with Cisco enic and VFs Message-Id: <20140422141750.9fa985b939c0967ab8384b23@redhat.com> In-Reply-To: <20140422141425.127dabd3c63482a6a655469e@redhat.com> References: <20140422141425.127dabd3c63482a6a655469e@redhat.com> Mime-Version: 1.0 X-Scanned-By: MIMEDefang 2.68 on 10.5.11.24 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Tue, 22 Apr 2014 14:14:25 +1000 David Gibson wrote: [snip] Sorry, had the wrong mailer setting, which mangled the patch. Trying again: From a8c1396c45449c0692560844d148abe7d5d1c2cc Mon Sep 17 00:00:00 2001 From: David Gibson Date: Tue, 22 Apr 2014 14:13:16 +1000 Subject: [PATCH] rtnetlink: Warn when interface's information won't fit in our packet Without IFLA_EXT_MASK specified, the information reported for a single interface in response to RTM_GETLINK is expected to fit within a netlink packet of NLMSG_GOODSIZE. If it doesn't, however, things will go badly wrong, When listing all interfaces, netlink_dump() will incorrectly treat -EMSGSIZE on the first message in a packet as the end of the listing and omit information for that interface and all subsequent ones. This can cause getifaddrs(3) to enter an infinite loop. This patch won't fix the problem, but it will WARN_ON() making it easier to track down what's going wrong. Signed-off-by: David Gibson --- net/core/rtnetlink.c | 16 +++++++++++----- 1 file changed, 11 insertions(+), 5 deletions(-) diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c index d4ff417..5331db2 100644 --- a/net/core/rtnetlink.c +++ b/net/core/rtnetlink.c @@ -1198,6 +1198,7 @@ static int rtnl_dump_ifinfo(struct sk_buff *skb, struct netlink_callback *cb) struct hlist_head *head; struct nlattr *tb[IFLA_MAX+1]; u32 ext_filter_mask = 0; + int err; s_h = cb->args[0]; s_idx = cb->args[1]; @@ -1218,11 +1219,16 @@ static int rtnl_dump_ifinfo(struct sk_buff *skb, struct netlink_callback *cb) hlist_for_each_entry_rcu(dev, head, index_hlist) { if (idx < s_idx) goto cont; - if (rtnl_fill_ifinfo(skb, dev, RTM_NEWLINK, - NETLINK_CB(cb->skb).portid, - cb->nlh->nlmsg_seq, 0, - NLM_F_MULTI, - ext_filter_mask) <= 0) + err = rtnl_fill_ifinfo(skb, dev, RTM_NEWLINK, + NETLINK_CB(cb->skb).portid, + cb->nlh->nlmsg_seq, 0, + NLM_F_MULTI, + ext_filter_mask); + /* If we ran out of room on the first message, + * we're in trouble */ + WARN_ON((err == -EMSGSIZE) && (skb->len == 0)); + + if (err <= 0) goto out; nl_dump_check_consistent(cb, nlmsg_hdr(skb));