commit 8c1d598338077d397aed25fe4840e4d4b51ba79c
Author: Patrick McHardy <kaber@trash.net>
Date:   Tue Dec 9 21:52:00 2008 +0100

    atk5k: fix FCS corruption for ACKs
    
    The trailing FCS value is not aliged when no payload is present. Don't try
    to remove padding to avoid corrupting it.

    Kernel Bugzilla #12101
    
    Signed-off-by: Patrick McHardy <kaber@trash.net>

diff --git a/drivers/net/wireless/ath5k/base.c b/drivers/net/wireless/ath5k/base.c
index d9e1980..940c724 100644
--- a/drivers/net/wireless/ath5k/base.c
+++ b/drivers/net/wireless/ath5k/base.c
@@ -1752,7 +1752,7 @@ accept:
 		 * not multiples of 4 - remove it
 		 */
 		hdrlen = ieee80211_get_hdrlen_from_skb(skb);
-		if (hdrlen & 3) {
+		if (hdrlen & 3 && hdrlen != rs.rs_datalen - FCS_LEN) {
 			pad = hdrlen % 4;
 			memmove(skb->data + pad, skb->data, hdrlen);
 			skb_pull(skb, pad);