ath9k: fix a use-after-free-bug when ath_tx_setup_buffer() fails

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@openwrt.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/drivers/net/wireless/ath/ath9k/xmit.c b/drivers/net/wireless/ath/ath9k/xmit.c
index 03b0a65..76fd277 100644 (file)
--- a/drivers/net/wireless/ath/ath9k/xmit.c
+++ b/drivers/net/wireless/ath/ath9k/xmit.c
@@ -64,7 +64,8 @@ static void ath_tx_update_baw(struct ath_softc *sc, struct ath_atx_tid *tid,
 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 @@ static enum ATH_AGGR_STATUS ath_tx_form_aggr(struct ath_softc *sc,
                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 @@ static void ath_tx_send_ampdu(struct ath_softc *sc, struct ath_atx_tid *tid,
                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 @@ static void ath_tx_send_normal(struct ath_softc *sc, struct ath_txq *txq,
 
        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 @@ u8 ath_txchainmask_reduction(struct ath_softc *sc, u8 chainmask, u32 rate)
 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 @@ static struct ath_buf *ath_tx_setup_buffer(struct ath_softc *sc,
        return bf;
 
 error:
+       if (dequeue)
+               __skb_unlink(skb, &tid->buf_q);
        dev_kfree_skb_any(skb);
        return NULL;
 }
@@ -1833,7 +1837,7 @@ static void ath_tx_start_dma(struct ath_softc *sc, struct sk_buff *skb,
                 */
                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;