1 files changed, 18 insertions, 3 deletions

diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
index df6aac523532..7a637b80a62e 100644
--- a/net/mac80211/tx.c
+++ b/net/mac80211/tx.c
@@ -1737,15 +1737,13 @@ netdev_tx_t ieee80211_subif_start_xmit(struct sk_buff *skb,
         int nh_pos, h_pos;
         struct sta_info *sta = NULL;
         u32 sta_flags = 0;
+        struct sk_buff *tmp_skb;
 
         if (unlikely(skb->len < ETH_HLEN)) {
                 ret = NETDEV_TX_OK;
                 goto fail;
         }
 
-        nh_pos = skb_network_header(skb) - skb->data;
-        h_pos = skb_transport_header(skb) - skb->data;
-
         /* convert Ethernet header to proper 802.11 header (based on
          * operation mode) */
         ethertype = (skb->data[12] << 8) | skb->data[13];
@@ -1918,6 +1916,20 @@ netdev_tx_t ieee80211_subif_start_xmit(struct sk_buff *skb,
                 goto fail;
         }
 
+        /*
+         * If the skb is shared we need to obtain our own copy.
+         */
+        if (skb_shared(skb)) {
+                tmp_skb = skb;
+                skb = skb_copy(skb, GFP_ATOMIC);
+                kfree_skb(tmp_skb);
+
+                if (!skb) {
+                        ret = NETDEV_TX_OK;
+                        goto fail;
+                }
+        }
+
         hdr.frame_control = fc;
         hdr.duration_id = 0;
         hdr.seq_ctrl = 0;
@@ -1936,6 +1948,9 @@ netdev_tx_t ieee80211_subif_start_xmit(struct sk_buff *skb,
                 encaps_len = 0;
         }
 
+        nh_pos = skb_network_header(skb) - skb->data;
+        h_pos = skb_transport_header(skb) - skb->data;
+
         skb_pull(skb, skip_header_bytes);
         nh_pos -= skip_header_bytes;
         h_pos -= skip_header_bytes;