mac80211: allocate tailroom for forwarded mesh packets

commit 51d0af22 upstream.

Forwarded packets enter the tx path through ieee80211_add_pending_skb,
which skips the ieee80211_skb_resize call.
Fixes WARN_ON in ccmp_encrypt_skb and resulting packet loss.

Cc: stable@vger.kernel.org
Signed-off-by: Felix Fietkau <nbd@nbd.name>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

net/mac80211/rx.c

@@ -2598,6 +2598,7 @@ ieee80211_rx_h_mesh_fwding(struct ieee80211_rx_data *rx)
 	struct ieee80211_sub_if_data *sdata = rx->sdata;
 	struct ieee80211_if_mesh *ifmsh = &sdata->u.mesh;
 	u16 ac, q, hdrlen;
+	int tailroom = 0;
 
 	hdr = (struct ieee80211_hdr *) skb->data;
 	hdrlen = ieee80211_hdrlen(hdr->frame_control);
@@ -2684,8 +2685,12 @@ ieee80211_rx_h_mesh_fwding(struct ieee80211_rx_data *rx)
 	if (!ifmsh->mshcfg.dot11MeshForwarding)
 		goto out;
 
+	if (sdata->crypto_tx_tailroom_needed_cnt)
+		tailroom = IEEE80211_ENCRYPT_TAILROOM;
+
 	fwd_skb = skb_copy_expand(skb, local->tx_headroom +
-				       sdata->encrypt_headroom, 0, GFP_ATOMIC);
+				       sdata->encrypt_headroom,
+				  tailroom, GFP_ATOMIC);
 	if (!fwd_skb)
 		goto out;