ath5k: check return value of ieee80211_get_tx_rate

This avoids a NULL pointer dereference as reported here:

	https://bugzilla.redhat.com/show_bug.cgi?id=625889

When the WARN condition is hit in ieee80211_get_tx_rate, it will return
NULL.  So, we need to check the return value and avoid dereferencing it
in that case.

Signed-off-by: John W. Linville <linville@tuxdriver.com>
Cc: stable@kernel.org
Acked-by: Bob Copeland <me@bobcopeland.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/drivers/net/wireless/ath/ath5k/base.c b/drivers/net/wireless/ath/ath5k/base.c
index 373dcfec689..d77ce9906b6 100644
--- a/drivers/net/wireless/ath/ath5k/base.c
+++ b/drivers/net/wireless/ath/ath5k/base.c
@@ -1327,6 +1327,10 @@ ath5k_txbuf_setup(struct ath5k_softc *sc, struct ath5k_buf *bf,
                         PCI_DMA_TODEVICE);
 
         rate = ieee80211_get_tx_rate(sc->hw, info);
+        if (!rate) {
+                ret = -EINVAL;
+                goto err_unmap;
+        }
 
         if (info->flags & IEEE80211_TX_CTL_NO_ACK)
                 flags |= AR5K_TXDESC_NOACK;