[ 26/82] ath9k: fix a use-after-free-bug when ath_tx_setup_buffer() fails

[Ben Hutchings]

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

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

From: Felix Fietkau <nbd@xxxxxxxxxxx>

commit 81357a281dcc454841532c46b30e6f2ba12b73ea upstream.

ath_tx_setup_buffer() can fail if there is no ath_buf left, or if mapping DMA
failed. In this case it frees the skb passed to it.
If ath_tx_setup_buffer is called from ath_tx_form_aggr, the skb is still
linked into the tid buffer list and must be dequeued before being released.

Signed-off-by: Felix Fietkau <nbd@xxxxxxxxxxx>
Signed-off-by: John W. Linville <linville@xxxxxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 drivers/net/wireless/ath/ath9k/xmit.c |   16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

--- a/drivers/net/wireless/ath/ath9k/xmit.c
+++ b/drivers/net/wireless/ath/ath9k/xmit.c
@@ -64,7 +64,8 @@
 static struct ath_buf *ath_tx_setup_buffer(struct ath_softc *sc,
 					   struct ath_txq *txq,
 					   struct ath_atx_tid *tid,
-					   struct sk_buff *skb);
+					   struct sk_buff *skb,
+					   bool dequeue);
 
 enum {
 	MCS_HT20,
@@ -761,7 +762,7 @@
 		fi = get_frame_info(skb);
 		bf = fi->bf;
 		if (!fi->bf)
-			bf = ath_tx_setup_buffer(sc, txq, tid, skb);
+			bf = ath_tx_setup_buffer(sc, txq, tid, skb, true);
 
 		if (!bf)
 			continue;
@@ -1669,7 +1670,7 @@
 		return;
 	}
 
-	bf = ath_tx_setup_buffer(sc, txctl->txq, tid, skb);
+	bf = ath_tx_setup_buffer(sc, txctl->txq, tid, skb, false);
 	if (!bf)
 		return;
 
@@ -1696,7 +1697,7 @@
 
 	bf = fi->bf;
 	if (!bf)
-		bf = ath_tx_setup_buffer(sc, txq, tid, skb);
+		bf = ath_tx_setup_buffer(sc, txq, tid, skb, false);
 
 	if (!bf)
 		return;
@@ -1761,7 +1762,8 @@
 static struct ath_buf *ath_tx_setup_buffer(struct ath_softc *sc,
 					   struct ath_txq *txq,
 					   struct ath_atx_tid *tid,
-					   struct sk_buff *skb)
+					   struct sk_buff *skb,
+					   bool dequeue)
 {
 	struct ath_common *common = ath9k_hw_common(sc->sc_ah);
 	struct ath_frame_info *fi = get_frame_info(skb);
@@ -1802,6 +1804,8 @@
 	return bf;
 
 error:
+	if (dequeue)
+		__skb_unlink(skb, &tid->buf_q);
 	dev_kfree_skb_any(skb);
 	return NULL;
 }
@@ -1833,7 +1837,7 @@
 		 */
 		ath_tx_send_ampdu(sc, tid, skb, txctl);
 	} else {
-		bf = ath_tx_setup_buffer(sc, txctl->txq, tid, skb);
+		bf = ath_tx_setup_buffer(sc, txctl->txq, tid, skb, false);
 		if (!bf)
 			goto out;
 


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