[PATCH] mac80211: fix oops in ieee80211_beacon_get_tim

[Christian Lamparter <chunkeey@googlemail.com>]

This patch fixes a crash which is triggered
by __ieee80211_beacon_get returning NULL.
This causes sky_copy to crash later unless
the hardware supports BEACON_TX_STATUS
feature.

Signed-off-by: Christian Lamparter <chunkeey@googlemail.com>
---
"mac80211: Copy tx'ed beacons to monitor mode" added the skb_copy.
There are few other possibilities to do this. This is just one.
---
 net/mac80211/tx.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
index f7317a7..666e46b 100644
--- a/net/mac80211/tx.c
+++ b/net/mac80211/tx.c
@@ -3530,6 +3530,9 @@ struct sk_buff *ieee80211_beacon_get_tim(struct ieee80211_hw *hw,
 	struct ieee80211_supported_band *sband;
 	int shift;
 
+	if (!bcn)
+		return bcn;
+
 	if (tim_offset)
 		*tim_offset = offs.tim_offset;
 
-- 
2.5.3