wifi: cfg80211: fix receiving mesh packets without RFC1042 header

Fix ethernet header length field after stripping the mesh header

Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/all/CT5GNZSK28AI.2K6M69OXM9RW5@syracuse/
Fixes: 986e43b1 ("wifi: mac80211: fix receiving A-MSDU frames on mesh interfaces")
Reported-and-tested-by: Nicolas Escande <nico.escande@gmail.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>
Link: https://lore.kernel.org/r/20230711115052.68430-1-nbd@nbd.nameSigned-off-by: Jakub Kicinski <kuba@kernel.org>

net/wireless/util.c

@@ -580,6 +580,8 @@ int ieee80211_strip_8023_mesh_hdr(struct sk_buff *skb)
 		hdrlen += ETH_ALEN + 2;
 	else if (!pskb_may_pull(skb, hdrlen))
 		return -EINVAL;
+	else
+		payload.eth.h_proto = htons(skb->len - hdrlen);
 
 	mesh_addr = skb->data + sizeof(payload.eth) + ETH_ALEN;
 	switch (payload.flags & MESH_FLAGS_AE) {