From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alexander Duyck Subject: [net PATCH] flow_dissector: Fix unaligned access in __skb_flow_dissector when used by eth_get_headlen Date: Fri, 29 Jan 2016 18:49:05 -0800 Message-ID: <20160130024556.6227.51798.stgit@localhost.localdomain> References: <20160129180651.GA17127@oracle.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Cc: Sowmini Varadhan , eric.dumazet@gmail.com, tom@herbertland.com To: netdev@vger.kernel.org, davem@davemloft.net, alexander.duyck@gmail.com Return-path: Received: from mail-pa0-f52.google.com ([209.85.220.52]:33096 "EHLO mail-pa0-f52.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753158AbcA3CtI (ORCPT ); Fri, 29 Jan 2016 21:49:08 -0500 Received: by mail-pa0-f52.google.com with SMTP id cy9so50649849pac.0 for ; Fri, 29 Jan 2016 18:49:07 -0800 (PST) In-Reply-To: <20160129180651.GA17127@oracle.com> Sender: netdev-owner@vger.kernel.org List-ID: This patch fixes an issue with unaligned accesses when using eth_get_headlen on a page that was DMA aligned instead of being IP aligned. The fact is when trying to check the length we don't need to be looking at the flow label so we can reorder the checks to first check if we are supposed to gather the flow label and then make the call to actually get it. Reported-by: Sowmini Varadhan Signed-off-by: Alexander Duyck --- net/core/flow_dissector.c | 15 ++++++++------- 1 file changed, 8 insertions(+), 7 deletions(-) diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c index d79699c9d1b9..f09114f8ee33 100644 --- a/net/core/flow_dissector.c +++ b/net/core/flow_dissector.c @@ -208,7 +208,6 @@ ip: case htons(ETH_P_IPV6): { const struct ipv6hdr *iph; struct ipv6hdr _iph; - __be32 flow_label; ipv6: iph = __skb_header_pointer(skb, nhoff, sizeof(_iph), data, hlen, &_iph); @@ -230,17 +229,19 @@ ipv6: key_control->addr_type = FLOW_DISSECTOR_KEY_IPV6_ADDRS; } - flow_label = ip6_flowlabel(iph); - if (flow_label) { - if (dissector_uses_key(flow_dissector, - FLOW_DISSECTOR_KEY_FLOW_LABEL)) { + if (dissector_uses_key(flow_dissector, + FLOW_DISSECTOR_KEY_FLOW_LABEL)) { + __be32 flow_label = ip6_flowlabel(iph); + + if (flow_label) { key_tags = skb_flow_dissector_target(flow_dissector, FLOW_DISSECTOR_KEY_FLOW_LABEL, target_container); key_tags->flow_label = ntohl(flow_label); + + if (flags & FLOW_DISSECTOR_F_STOP_AT_FLOW_LABEL) + goto out_good; } - if (flags & FLOW_DISSECTOR_F_STOP_AT_FLOW_LABEL) - goto out_good; } if (flags & FLOW_DISSECTOR_F_STOP_AT_L3)