[PATCH] hostap: Fix skb->cb use for TX meta data

Old AP mode code for power saving was using skb->cb for couple of
flags before the more generic 802.11 TX code started using the same
buffer for struct hostap_skb_tx_data. This resulted in the power save
code corrupting the magic value in beginning of the buffer and TX code
dropping the power saved packets because of this for the case where
STAs send PS-Poll frames with PwrMgmt flag set.

This patch modifies the power save code to use the same struct
hostap_skb_tx_data as rest of the TX path in order to avoid corrupting
the data in skb->cb.

In addition, this patch reorders fields in the structure and makes
them use smaller types in order to make the structure fit in skb->cb
on 64-bit hosts.

Signed-off-by: Jouni Malinen <jkmaline@cc.hut.fi>
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>

1 files changed, 15 insertions, 15 deletions

diff --git a/drivers/net/wireless/hostap/hostap_ap.c b/drivers/net/wireless/hostap/hostap_ap.c
index c9aeefcd761..550855a9150 100644
--- a/drivers/net/wireless/hostap/hostap_ap.c
+++ b/drivers/net/wireless/hostap/hostap_ap.c
@@ -1840,6 +1840,8 @@ static void ap_handle_dropped_data(local_info_t *local,
 static void pspoll_send_buffered(local_info_t *local, struct sta_info *sta,
 				 struct sk_buff *skb)
 {
+	struct hostap_skb_tx_data *meta;
+
 	if (!(sta->flags & WLAN_STA_PS)) {
 		/* Station has moved to non-PS mode, so send all buffered
 		 * frames using normal device queue. */
@@ -1849,11 +1851,11 @@ static void pspoll_send_buffered(local_info_t *local, struct sta_info *sta,
 
 	/* add a flag for hostap_handle_sta_tx() to know that this skb should
 	 * be passed through even though STA is using PS */
-	memcpy(skb->cb, AP_SKB_CB_MAGIC, AP_SKB_CB_MAGIC_LEN);
-	skb->cb[AP_SKB_CB_MAGIC_LEN] = AP_SKB_CB_BUFFERED_FRAME;
+	meta = (struct hostap_skb_tx_data *) skb->cb;
+	meta->flags |= HOSTAP_TX_FLAGS_BUFFERED_FRAME;
 	if (!skb_queue_empty(&sta->tx_buf)) {
 		/* indicate to STA that more frames follow */
-		skb->cb[AP_SKB_CB_MAGIC_LEN] |= AP_SKB_CB_ADD_MOREDATA;
+		meta->flags |= HOSTAP_TX_FLAGS_ADD_MOREDATA;
 	}
 	dev_queue_xmit(skb);
 }
@@ -2707,7 +2709,8 @@ ap_tx_ret hostap_handle_sta_tx(local_info_t *local, struct hostap_tx_data *tx)
 		atomic_inc(&sta->users);
 	spin_unlock(&local->ap->sta_table_lock);
 
-	if (local->iw_mode == IW_MODE_MASTER && sta == NULL && !meta->wds &&
+	if (local->iw_mode == IW_MODE_MASTER && sta == NULL &&
+	    !(meta->flags & HOSTAP_TX_FLAGS_WDS) &&
 	    meta->iface->type != HOSTAP_INTERFACE_MASTER &&
 	    meta->iface->type != HOSTAP_INTERFACE_AP) {
 #if 0
@@ -2743,18 +2746,15 @@ ap_tx_ret hostap_handle_sta_tx(local_info_t *local, struct hostap_tx_data *tx)
 	if (!(sta->flags & WLAN_STA_PS))
 		goto out;
 
-	if (memcmp(skb->cb, AP_SKB_CB_MAGIC, AP_SKB_CB_MAGIC_LEN) == 0) {
-		if (skb->cb[AP_SKB_CB_MAGIC_LEN] & AP_SKB_CB_ADD_MOREDATA) {
-			/* indicate to STA that more frames follow */
-			hdr->frame_control |=
-				__constant_cpu_to_le16(WLAN_FC_MOREDATA);
-		}
+	if (meta->flags & HOSTAP_TX_FLAGS_ADD_MOREDATA) {
+		/* indicate to STA that more frames follow */
+		hdr->frame_control |= __constant_cpu_to_le16(WLAN_FC_MOREDATA);
+	}
 
-		if (skb->cb[AP_SKB_CB_MAGIC_LEN] & AP_SKB_CB_BUFFERED_FRAME) {
-			/* packet was already buffered and now send due to
-			 * PS poll, so do not rebuffer it */
-			goto out;
-		}
+	if (meta->flags & HOSTAP_TX_FLAGS_BUFFERED_FRAME) {
+		/* packet was already buffered and now send due to
+		 * PS poll, so do not rebuffer it */
+		goto out;
 	}
 
 	if (skb_queue_len(&sta->tx_buf) >= STA_MAX_TX_BUFFER) {