b43legacy: Fix DMA TX bounce buffer copying

This patch is adapted from the submission by Michael Buesch <mb@bu3sch.de>
for a bounce-buffer copying problem with b43.

Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 15 insertions, 2 deletions

diff --git a/drivers/net/wireless/b43legacy/dma.c b/drivers/net/wireless/b43legacy/dma.c
index 866403415811..0a86bdf53154 100644
--- a/drivers/net/wireless/b43legacy/dma.c
+++ b/drivers/net/wireless/b43legacy/dma.c
@@ -1240,8 +1240,9 @@ struct b43legacy_dmaring *parse_cookie(struct b43legacy_wldev *dev,
 }
 
 static int dma_tx_fragment(struct b43legacy_dmaring *ring,
-                            struct sk_buff *skb)
+                            struct sk_buff **in_skb)
 {
+        struct sk_buff *skb = *in_skb;
         const struct b43legacy_dma_ops *ops = ring->ops;
         struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
         u8 *header;
@@ -1305,8 +1306,14 @@ static int dma_tx_fragment(struct b43legacy_dmaring *ring,
                 }
 
                 memcpy(skb_put(bounce_skb, skb->len), skb->data, skb->len);
+                memcpy(bounce_skb->cb, skb->cb, sizeof(skb->cb));
+                bounce_skb->dev = skb->dev;
+                skb_set_queue_mapping(bounce_skb, skb_get_queue_mapping(skb));
+                info = IEEE80211_SKB_CB(bounce_skb);
+
                 dev_kfree_skb_any(skb);
                 skb = bounce_skb;
+                *in_skb = bounce_skb;
                 meta->skb = skb;
                 meta->dmaaddr = map_descbuffer(ring, skb->data, skb->len, 1);
                 if (b43legacy_dma_mapping_error(ring, meta->dmaaddr, skb->len, 1)) {
@@ -1360,8 +1367,10 @@ int b43legacy_dma_tx(struct b43legacy_wldev *dev,
                      struct sk_buff *skb)
 {
         struct b43legacy_dmaring *ring;
+        struct ieee80211_hdr *hdr;
         int err = 0;
         unsigned long flags;
+        struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
 
         ring = priority_to_txring(dev, skb_get_queue_mapping(skb));
         spin_lock_irqsave(&ring->lock, flags);
@@ -1386,7 +1395,11 @@ int b43legacy_dma_tx(struct b43legacy_wldev *dev,
                 goto out_unlock;
         }
 
-        err = dma_tx_fragment(ring, skb);
+        /* dma_tx_fragment might reallocate the skb, so invalidate pointers pointing
+         * into the skb data or cb now. */
+        hdr = NULL;
+        info = NULL;
+        err = dma_tx_fragment(ring, &skb);
         if (unlikely(err == -ENOKEY)) {
                 /* Drop this packet, as we don't have the encryption key
                  * anymore and must not transmit it unencrypted. */