This is a note to let you know that I've just added the patch titled
net: 802: LLC+SNAP OID:PID lookup on start of skb data
to the 5.4-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:
net-802-llc-snap-oid-pid-lookup-on-start-of-skb-data.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit a482e201b6e5fb7ba1c37e980c7d5af28b91303e
Author: Antonio Pastor <antonio.pastor@xxxxxxxxx>
Date: Thu Jan 2 20:23:00 2025 -0500
net: 802: LLC+SNAP OID:PID lookup on start of skb data
[ Upstream commit 1e9b0e1c550c42c13c111d1a31e822057232abc4 ]
802.2+LLC+SNAP frames received by napi_complete_done() with GRO and DSA
have skb->transport_header set two bytes short, or pointing 2 bytes
before network_header & skb->data. This was an issue as snap_rcv()
expected offset to point to SNAP header (OID:PID), causing packet to
be dropped.
A fix at llc_fixup_skb() (a024e377efed) resets transport_header for any
LLC consumers that may care about it, and stops SNAP packets from being
dropped, but doesn't fix the problem which is that LLC and SNAP should
not use transport_header offset.
Ths patch eliminates the use of transport_header offset for SNAP lookup
of OID:PID so that SNAP does not rely on the offset at all.
The offset is reset after pull for any SNAP packet consumers that may
(but shouldn't) use it.
Fixes: fda55eca5a33 ("net: introduce skb_transport_header_was_set()")
Signed-off-by: Antonio Pastor <antonio.pastor@xxxxxxxxx>
Reviewed-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Link: https://patch.msgid.link/20250103012303.746521-1-antonio.pastor@xxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/net/802/psnap.c b/net/802/psnap.c
index 40ab2aea7b31..7431ec077273 100644
--- a/net/802/psnap.c
+++ b/net/802/psnap.c
@@ -55,11 +55,11 @@ static int snap_rcv(struct sk_buff *skb, struct net_device *dev,
goto drop;
rcu_read_lock();
- proto = find_snap_client(skb_transport_header(skb));
+ proto = find_snap_client(skb->data);
if (proto) {
/* Pass the frame on. */
- skb->transport_header += 5;
skb_pull_rcsum(skb, 5);
+ skb_reset_transport_header(skb);
rc = proto->rcvfunc(skb, dev, &snap_packet_type, orig_dev);
}
rcu_read_unlock();
