Revert "net: Fix skb_set_peeked use-after-free bug"

This reverts commit d9a11334.

net/core/datagram.c

@@ -130,35 +130,6 @@ static int wait_for_more_packets(struct sock *sk, int *err, long *timeo_p,
 	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
@@ -193,9 +164,7 @@ static int skb_set_peeked(struct sk_buff *skb)
 struct sk_buff *__skb_recv_datagram(struct sock *sk, unsigned int flags,
 				    int *peeked, int *off, int *err)
 {
-	struct sk_buff_head *queue = &sk->sk_receive_queue;
 	struct sk_buff *skb, *last;
-	unsigned long cpu_flags;
 	long timeo;
 	/*
 	 * Caller is allowed not to check sk->sk_err before skb_recv_datagram()
@@ -214,6 +183,8 @@ struct sk_buff *__skb_recv_datagram(struct sock *sk, unsigned int flags,
 		 * Look at current nfs client by the way...
 		 * However, this function was correct in any case. 8)
 		 */
+		unsigned long cpu_flags;
+		struct sk_buff_head *queue = &sk->sk_receive_queue;
 		int _off = *off;
 
 		last = (struct sk_buff *)queue;
@@ -227,11 +198,7 @@ struct sk_buff *__skb_recv_datagram(struct sock *sk, unsigned int flags,
 					_off -= skb->len;
 					continue;
 				}
-
-				error = skb_set_peeked(skb);
-				if (error)
-					goto unlock_err;
-
+				skb->peeked = 1;
 				atomic_inc(&skb->users);
 			} else
 				__skb_unlink(skb, queue);
@@ -255,8 +222,6 @@ struct sk_buff *__skb_recv_datagram(struct sock *sk, unsigned int flags,
 
 	return NULL;
 
-unlock_err:
-	spin_unlock_irqrestore(&queue->lock, cpu_flags);
 no_packet:
 	*err = error;
 	return NULL;