zd1211rw: fix alignment for QOS and WDS frames

This patch fixes RX packet alignment issues in the zd1211rw driver.
This is based on a patch by Johannes Berg.

Signed-off-by: Michael Buesch <mb@bu3sch.de>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 16 insertions, 1 deletions

diff --git a/drivers/net/wireless/zd1211rw/zd_mac.c b/drivers/net/wireless/zd1211rw/zd_mac.c
index 14fb727583d5..7b8693050480 100644
--- a/drivers/net/wireless/zd1211rw/zd_mac.c
+++ b/drivers/net/wireless/zd1211rw/zd_mac.c
@@ -623,6 +623,8 @@ int zd_mac_rx(struct ieee80211_hw *hw, const u8 *buffer, unsigned int length)
         const struct rx_status *status;
         struct sk_buff *skb;
         int bad_frame = 0;
+        u16 fc;
+        bool is_qos, is_4addr, need_padding;
 
         if (length < ZD_PLCP_HEADER_SIZE + 10 /* IEEE80211_1ADDR_LEN */ +
                      FCS_LEN + sizeof(struct rx_status))
@@ -674,9 +676,22 @@ int zd_mac_rx(struct ieee80211_hw *hw, const u8 *buffer, unsigned int length)
                         && !mac->pass_ctrl)
                 return 0;
 
-        skb = dev_alloc_skb(length);
+        fc = le16_to_cpu(*((__le16 *) buffer));
+
+        is_qos = ((fc & IEEE80211_FCTL_FTYPE) == IEEE80211_FTYPE_DATA) &&
+                 ((fc & IEEE80211_FCTL_STYPE) == IEEE80211_STYPE_QOS_DATA);
+        is_4addr = (fc & (IEEE80211_FCTL_TODS | IEEE80211_FCTL_FROMDS)) ==
+                   (IEEE80211_FCTL_TODS | IEEE80211_FCTL_FROMDS);
+        need_padding = is_qos ^ is_4addr;
+
+        skb = dev_alloc_skb(length + (need_padding ? 2 : 0));
         if (skb == NULL)
                 return -ENOMEM;
+        if (need_padding) {
+                /* Make sure the the payload data is 4 byte aligned. */
+                skb_reserve(skb, 2);
+        }
+
         memcpy(skb_put(skb, length), buffer, length);
 
         ieee80211_rx_irqsafe(hw, skb, &stats);