mac80211: preserve more bits when building QoS header

Michael Braun reported that when trying to inject A-MSDUs over
monitor interfaces, the frame doesn't come out right since the
QoS header A-MSDU bit is overwritten.

Rather than adding that bit specifically simply preserve those
bits that we don't set here, since we typically get here with
a zeroed-out QoS header anyway.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>

diff --git a/net/mac80211/wme.c b/net/mac80211/wme.c
index 9eb0aee9105b398b442380315ec758a430a103b1..3e3d3014e9ab6d026a13232ce6cb930b9fc87093 100644 (file)
--- a/net/mac80211/wme.c
+++ b/net/mac80211/wme.c
@@ -236,26 +236,35 @@ void ieee80211_set_qos_hdr(struct ieee80211_sub_if_data *sdata,
 {
        struct ieee80211_hdr *hdr = (void *)skb->data;
        struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
+       u8 tid = skb->priority & IEEE80211_QOS_CTL_TAG1D_MASK;
+       u8 flags;
        u8 *p;
-       u8 ack_policy, tid;
 
        if (!ieee80211_is_data_qos(hdr->frame_control))
                return;
 
        p = ieee80211_get_qos_ctl(hdr);
-       tid = skb->priority & IEEE80211_QOS_CTL_TAG1D_MASK;
 
-       /* preserve EOSP bit */
-       ack_policy = *p & IEEE80211_QOS_CTL_EOSP;
+       /* set up the first byte */
+
+       /*
+        * preserve everything but the TID and ACK policy
+        * (which we both write here)
+        */
+       flags = *p & ~(IEEE80211_QOS_CTL_TID_MASK |
+                      IEEE80211_QOS_CTL_ACK_POLICY_MASK);
 
        if (is_multicast_ether_addr(hdr->addr1) ||
            sdata->noack_map & BIT(tid)) {
-               ack_policy |= IEEE80211_QOS_CTL_ACK_POLICY_NOACK;
+               flags |= IEEE80211_QOS_CTL_ACK_POLICY_NOACK;
                info->flags |= IEEE80211_TX_CTL_NO_ACK;
        }
 
-       /* qos header is 2 bytes */
-       *p++ = ack_policy | tid;
+       *p = flags | tid;
+
+       /* set up the second byte */
+       p++;
+
        if (ieee80211_vif_is_mesh(&sdata->vif)) {
                /* preserve RSPI and Mesh PS Level bit */
                *p &= ((IEEE80211_QOS_CTL_RSPI |