mac80211: allocate tailroom for forwarded mesh packets

Fixes a warning + packet loss on encrypted mesh networks with forwarding

Signed-off-by: Felix Fietkau <nbd@nbd.name>

package/kernel/mac80211/patches/subsys/302-mac80211-allocate-tailroom-for-forwarded-mesh-packet.patch

@@ -0,0 +1,37 @@
+From: Felix Fietkau <nbd@nbd.name>
+Date: Fri, 22 Feb 2019 13:21:15 +0100
+Subject: [PATCH] mac80211: allocate tailroom for forwarded mesh packets
+
+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>
+---
+
+--- a/net/mac80211/rx.c
++++ b/net/mac80211/rx.c
+@@ -2598,6 +2598,7 @@ ieee80211_rx_h_mesh_fwding(struct ieee80
+ 	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 ieee80
+ 	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;
+