ath9k: Check for NULL sta in ath_tx_start

It can be NULL according to docs, and logging showed it
to be NULL in practice.

Signed-off-by: Ben Greear <greearb@candelatech.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

diff --git a/drivers/net/wireless/ath/ath9k/xmit.c b/drivers/net/wireless/ath/ath9k/xmit.c
index 16d83d0..bce313e 100644 (file)
--- a/drivers/net/wireless/ath/ath9k/xmit.c
+++ b/drivers/net/wireless/ath/ath9k/xmit.c
@@ -1740,7 +1740,10 @@ int ath_tx_start(struct ieee80211_hw *hw, struct sk_buff *skb,
        int frmlen = skb->len + FCS_LEN;
        int q;
 
-       txctl->an = (struct ath_node *)sta->drv_priv;
+       /* NOTE:  sta can be NULL according to net/mac80211.h */
+       if (sta)
+               txctl->an = (struct ath_node *)sta->drv_priv;
+
        if (info->control.hw_key)
                frmlen += info->control.hw_key->icv_len;