Patch "flow_dissector: Fix unaligned access in __skb_flow_dissector when used by eth_get_headlen" has been added to the 4.4-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    flow_dissector: Fix unaligned access in __skb_flow_dissector when used by eth_get_headlen

to the 4.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     flow_dissector-fix-unaligned-access-in-__skb_flow_dissector-when-used-by-eth_get_headlen.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From foo@baz Mon Feb 29 14:33:50 PST 2016
From: Alexander Duyck <aduyck@mirantis.com>
Date: Tue, 9 Feb 2016 02:49:54 -0800
Subject: flow_dissector: Fix unaligned access in __skb_flow_dissector when used by eth_get_headlen

From: Alexander Duyck <aduyck@mirantis.com>

[ Upstream commit 461547f3158978c180d74484d58e82be9b8e7357 ]

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.

v2:  Updated path so that either STOP_AT_FLOW_LABEL or KEY_FLOW_LABEL can
     cause us to check for the flow label.

Reported-by: Sowmini Varadhan <sowmini.varadhan@oracle.com>
Signed-off-by: Alexander Duyck <aduyck@mirantis.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/core/flow_dissector.c |    9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

--- 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);
@@ -230,8 +229,12 @@ 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) ||
+		     (flags & FLOW_DISSECTOR_F_STOP_AT_FLOW_LABEL)) &&
+		    ip6_flowlabel(iph)) {
+			__be32 flow_label = ip6_flowlabel(iph);
+
 			if (dissector_uses_key(flow_dissector,
 					       FLOW_DISSECTOR_KEY_FLOW_LABEL)) {
 				key_tags = skb_flow_dissector_target(flow_dissector,


Patches currently in stable-queue which might be from aduyck@mirantis.com are

queue-4.4/flow_dissector-fix-unaligned-access-in-__skb_flow_dissector-when-used-by-eth_get_headlen.patch
queue-4.4/net-copy-inner-l3-and-l4-headers-as-unaligned-on-gre-teb.patch