mac80211: fix rx data handling for non-data frames on multiple vifs

The loop that passes non-data frames to all relevant vifs inside the
__ieee80211_rx_handle_packet keeps a pointer to the previous sdata to
avoid having to make unnecessary copies of the frame it's handling.
This led to a bug that caused it to apply the ieee80211_rx_data state
to the wrong interface, thereby either missing the rx.sta pointer or
having it assigned where it shouldn't be.
This breaks (among other things) aggregation on some vifs, as action
frame exchages are dropped to the cooked monitor interface due to
rx->sta being NULL.
Fix this by restructuring the loop so that it prepares the rx data just
before making the skb copy and calling the rx handlers.

Cc: stable@kernel.org
Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

net/mac80211/rx.c

@@ -2348,22 +2348,6 @@ static void __ieee80211_rx_handle_packet(struct ieee80211_hw *hw,
 			    sdata->vif.type == NL80211_IFTYPE_AP_VLAN)
 				continue;
 
-			rx.sta = sta_info_get(sdata, hdr->addr2);
-
-			rx.flags |= IEEE80211_RX_RA_MATCH;
-			prepares = prepare_for_handlers(sdata, &rx, hdr);
-
-			if (!prepares)
-				continue;
-
-			if (status->flag & RX_FLAG_MMIC_ERROR) {
-				rx.sdata = sdata;
-				if (rx.flags & IEEE80211_RX_RA_MATCH)
-					ieee80211_rx_michael_mic_report(hdr,
-									&rx);
-				continue;
-			}
-
 			/*
 			 * frame is destined for this interface, but if it's
 			 * not also for the previous one we handle that after
@@ -2375,6 +2359,22 @@ static void __ieee80211_rx_handle_packet(struct ieee80211_hw *hw,
 				continue;
 			}
 
+			rx.sta = sta_info_get(prev, hdr->addr2);
+
+			rx.flags |= IEEE80211_RX_RA_MATCH;
+			prepares = prepare_for_handlers(prev, &rx, hdr);
+
+			if (!prepares)
+				goto next;
+
+			if (status->flag & RX_FLAG_MMIC_ERROR) {
+				rx.sdata = prev;
+				if (rx.flags & IEEE80211_RX_RA_MATCH)
+					ieee80211_rx_michael_mic_report(hdr,
+									&rx);
+				goto next;
+			}
+
 			/*
 			 * frame was destined for the previous interface
 			 * so invoke RX handlers for it
@@ -2387,11 +2387,22 @@ static void __ieee80211_rx_handle_packet(struct ieee80211_hw *hw,
 					       "multicast frame for %s\n",
 					       wiphy_name(local->hw.wiphy),
 					       prev->name);
-				continue;
+				goto next;
 			}
 			ieee80211_invoke_rx_handlers(prev, &rx, skb_new, rate);
+next:
 			prev = sdata;
 		}
+
+		if (prev) {
+			rx.sta = sta_info_get(prev, hdr->addr2);
+
+			rx.flags |= IEEE80211_RX_RA_MATCH;
+			prepares = prepare_for_handlers(prev, &rx, hdr);
+
+			if (!prepares)
+				prev = NULL;
+		}
 	}
 	if (prev)
 		ieee80211_invoke_rx_handlers(prev, &rx, skb, rate);