ath9k: fix access to a freed skb in ath_rx_tasklet()

Signed-off-by: Pavel Roskin <proski@gnu.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/ath9k/recv.c

@@ -493,6 +493,7 @@ int ath_rx_tasklet(struct ath_softc *sc, int flush)
 	int hdrlen, padsize, retval;
 	bool decrypt_error = false;
 	u8 keyix;
+	__le16 fc;
 
 	spin_lock_bh(&sc->rx.rxbuflock);
 
@@ -606,6 +607,7 @@ int ath_rx_tasklet(struct ath_softc *sc, int flush)
 		/* see if any padding is done by the hw and remove it */
 		hdr = (struct ieee80211_hdr *)skb->data;
 		hdrlen = ieee80211_get_hdrlen_from_skb(skb);
+		fc = hdr->frame_control;
 
 		/* The MAC header is padded to have 32-bit boundary if the
 		 * packet payload is non-zero. The general calculation for
@@ -690,7 +692,7 @@ int ath_rx_tasklet(struct ath_softc *sc, int flush)
 			sc->rx.rxotherant = 0;
 		}
 
-		if (ieee80211_is_beacon(hdr->frame_control) &&
+		if (ieee80211_is_beacon(fc) &&
 				(sc->sc_flags & SC_OP_WAIT_FOR_BEACON)) {
 			sc->sc_flags &= ~SC_OP_WAIT_FOR_BEACON;
 			ath9k_hw_setpower(sc->sc_ah, ATH9K_PM_NETWORK_SLEEP);