net: Clone skb before setting peeked flag

[pandora-kernel.git] / net / core / datagram.c

diff --git a/net/core/datagram.c b/net/core/datagram.c
index 68bbf9f..eaa1d32 100644 (file)
--- a/net/core/datagram.c
+++ b/net/core/datagram.c
@@ -128,6 +128,35 @@ out_noerr:
        goto out;
 }
 
+static int skb_set_peeked(struct sk_buff *skb)
+{
+       struct sk_buff *nskb;
+
+       if (skb->peeked)
+               return 0;
+
+       /* We have to unshare an skb before modifying it. */
+       if (!skb_shared(skb))
+               goto done;
+
+       nskb = skb_clone(skb, GFP_ATOMIC);
+       if (!nskb)
+               return -ENOMEM;
+
+       skb->prev->next = nskb;
+       skb->next->prev = nskb;
+       nskb->prev = skb->prev;
+       nskb->next = skb->next;
+
+       consume_skb(skb);
+       skb = nskb;
+
+done:
+       skb->peeked = 1;
+
+       return 0;
+}
+
 /**
  *     __skb_recv_datagram - Receive a datagram skbuff
  *     @sk: socket
@@ -160,7 +189,9 @@ out_noerr:
 struct sk_buff *__skb_recv_datagram(struct sock *sk, unsigned flags,
                                    int *peeked, int *err)
 {
+       struct sk_buff_head *queue = &sk->sk_receive_queue;
        struct sk_buff *skb;
+       unsigned long cpu_flags;
        long timeo;
        /*
         * Caller is allowed not to check sk->sk_err before skb_recv_datagram()
@@ -179,19 +210,21 @@ struct sk_buff *__skb_recv_datagram(struct sock *sk, unsigned flags,
                 * Look at current nfs client by the way...
                 * However, this function was correct in any case. 8)
                 */
-               unsigned long cpu_flags;
-
-               spin_lock_irqsave(&sk->sk_receive_queue.lock, cpu_flags);
-               skb = skb_peek(&sk->sk_receive_queue);
+               spin_lock_irqsave(&queue->lock, cpu_flags);
+               skb = skb_peek(queue);
                if (skb) {
                        *peeked = skb->peeked;
                        if (flags & MSG_PEEK) {
-                               skb->peeked = 1;
+
+                               error = skb_set_peeked(skb);
+                               if (error)
+                                       goto unlock_err;
+
                                atomic_inc(&skb->users);
                        } else
-                               __skb_unlink(skb, &sk->sk_receive_queue);
+                               __skb_unlink(skb, queue);
                }
-               spin_unlock_irqrestore(&sk->sk_receive_queue.lock, cpu_flags);
+               spin_unlock_irqrestore(&queue->lock, cpu_flags);
 
                if (skb)
                        return skb;
@@ -205,6 +238,8 @@ struct sk_buff *__skb_recv_datagram(struct sock *sk, unsigned flags,
 
        return NULL;
 
+unlock_err:
+       spin_unlock_irqrestore(&queue->lock, cpu_flags);
 no_packet:
        *err = error;
        return NULL;