netdev - [PATCH net-next 2/2] openvswitch: fix vlan subtraction from packet length

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <d998778ac99025ce3a703223903c294a2bb9be26.1475583870.git.jbenc@redhat.com>
Date:   Tue,  4 Oct 2016 14:30:02 +0200
From:   Jiri Benc <jbenc@...hat.com>
To:     netdev@...r.kernel.org
Cc:     pravin shelar <pshelar@....org>, Eric Garver <e@...g.me>
Subject: [PATCH net-next 2/2] openvswitch: fix vlan subtraction from packet length

When the packet has its vlan tag in skb->vlan_tci, the length of the VLAN
header is not counted in skb->len. It doesn't make sense to subtract it.

In addition, to honor the comment below the code, the VLAN header length
should not be subtracted if there's a vlan tag in skb->vlan_tci. This leads
to the code simply subtracting the Ethernet header length.

Fixes: 018c1dda5ff1 ("openvswitch: 802.1AD Flow handling, actions, vlan parsing, netlink attributes")
Signed-off-by: Jiri Benc <jbenc@...hat.com>
---
 net/openvswitch/vport.c | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/net/openvswitch/vport.c b/net/openvswitch/vport.c
index 8f198437c724..210bafc09bd8 100644
--- a/net/openvswitch/vport.c
+++ b/net/openvswitch/vport.c
@@ -483,17 +483,13 @@ EXPORT_SYMBOL_GPL(ovs_vport_deferred_free);
 
 static unsigned int packet_length(const struct sk_buff *skb)
 {
-	unsigned int length = skb->len - ETH_HLEN;
-
-	if (skb_vlan_tagged(skb))
-		length -= VLAN_HLEN;
-
 	/* Don't subtract for multiple VLAN tags. Most (all?) drivers allow
 	 * (ETH_LEN + VLAN_HLEN) in addition to the mtu value, but almost none
 	 * account for 802.1ad. e.g. is_skb_forwardable().
+	 * Note that the first VLAN tag is always in skb->vlan_tci, thus not
+	 * accounted for in skb->len.
 	 */
-
-	return length;
+	return skb->len - ETH_HLEN;
 }
 
 void ovs_vport_send(struct vport *vport, struct sk_buff *skb)
-- 
1.8.3.1