This is a note to let you know that I've just added the patch titled net: skip virtio_net_hdr_set_proto if protocol already set to the 4.19-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-skip-virtio_net_hdr_set_proto-if-protocol-alread.patch and it can be found in the queue-4.19 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit f3ff66a34c83e355ab4f79a552333a23ea16206f Author: Willem de Bruijn <willemb@xxxxxxxxxx> Date: Mon Dec 20 09:50:27 2021 -0500 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@xxxxxxxxxx> Link: https://lore.kernel.org/r/20211220145027.2784293-1-willemdebruijn.kernel@xxxxxxxxx Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/include/linux/virtio_net.h b/include/linux/virtio_net.h index 8874b278cd34a..faee73c084d49 100644 --- a/include/linux/virtio_net.h +++ b/include/linux/virtio_net.h @@ -25,6 +25,9 @@ static inline bool virtio_net_hdr_match_proto(__be16 protocol, __u8 gso_type) static inline int virtio_net_hdr_set_proto(struct sk_buff *skb, const struct virtio_net_hdr *hdr) { + if (skb->protocol) + return 0; + switch (hdr->gso_type & ~VIRTIO_NET_HDR_GSO_ECN) { case VIRTIO_NET_HDR_GSO_TCPV4: case VIRTIO_NET_HDR_GSO_UDP: