net: skip virtio_net_hdr_set_proto if protocol already set
authorWillem de Bruijn <willemb@google.com>
Mon, 20 Dec 2021 14:50:27 +0000 (09:50 -0500)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Wed, 29 Dec 2021 11:28:43 +0000 (12:28 +0100)
commitb99c71f9097829a6708eeb048395bb9e79d636fb
tree51a23c1dd854167fe76512942f6173c1ea21ccad
parent8ba353f553da916c94d7e2add2fa286f9d8eb340
net: skip virtio_net_hdr_set_proto if protocol already set

[ Upstream commit 1ed1d592113959f00cc552c3b9f47ca2d157768f ]

virtio_net_hdr_set_proto infers skb->protocol from the virtio_net_hdr
gso_type, to avoid packets getting dropped for lack of a proto type.

Its protocol choice is a guess, especially in the case of UFO, where
the single VIRTIO_NET_HDR_GSO_UDP label covers both UFOv4 and UFOv6.

Skip this best effort if the field is already initialized. Whether
explicitly from userspace, or implicitly based on an earlier call to
dev_parse_header_protocol (which is more robust, but was introduced
after this patch).

Fixes: 9d2f67e43b73 ("net/packet: fix packet drop as of virtio gso")
Signed-off-by: Willem de Bruijn <willemb@google.com>
Link: https://lore.kernel.org/r/20211220145027.2784293-1-willemdebruijn.kernel@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
include/linux/virtio_net.h