3.5.7.2 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Felix Fietkau <[email protected]>

commit 8c6e30936a7893a85f6222084f0f26aceb81137a upstream.

bf->bf_next is only while buffers are chained as part of an A-MPDU
in the tx queue. When a tid queue is flushed (e.g. on tearing down
an aggregation session), frames can be enqueued again as normal
transmission, without bf_next being cleared. This can lead to the
old pointer being dereferenced again later.

This patch might fix crashes and "Failed to stop TX DMA!" messages.

Signed-off-by: Felix Fietkau <[email protected]>
Signed-off-by: John W. Linville <[email protected]>
Signed-off-by: Herton Ronaldo Krzesinski <[email protected]>
---
 drivers/net/wireless/ath/ath9k/xmit.c |    2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/net/wireless/ath/ath9k/xmit.c 
b/drivers/net/wireless/ath/ath9k/xmit.c
index b78773b..11f252f 100644
--- a/drivers/net/wireless/ath/ath9k/xmit.c
+++ b/drivers/net/wireless/ath/ath9k/xmit.c
@@ -337,6 +337,7 @@ static struct ath_buf *ath_tx_get_buffer(struct ath_softc 
*sc)
        }
 
        bf = list_first_entry(&sc->tx.txbuf, struct ath_buf, list);
+       bf->bf_next = NULL;
        list_del(&bf->list);
 
        spin_unlock_bh(&sc->tx.txbuflock);
@@ -1760,6 +1761,7 @@ static void ath_tx_send_normal(struct ath_softc *sc, 
struct ath_txq *txq,
        list_add_tail(&bf->list, &bf_head);
        bf->bf_state.bf_type = 0;
 
+       bf->bf_next = NULL;
        bf->bf_lastbf = bf;
        ath_tx_fill_desc(sc, bf, txq, fi->framelen);
        ath_tx_txqaddbuf(sc, txq, &bf_head, false);
-- 
1.7.9.5

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