Merge tag 'v3.14.54' of git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable into linux-linaro-lsk-v3.14lsk-v3.14-15.10

This is the 3.14.54 stable release

* tag 'v3.14.54' of git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable: (115 commits)
  Linux 3.14.54
  NVMe: Initialize device reference count earlier
  udf: Check length of extended attributes and allocation descriptors
  x86/nmi/64: Use DF to avoid userspace RSP confusing nested NMI detection
  x86/nmi/64: Reorder nested NMI checks
  x86/nmi/64: Improve nested NMI comments
  x86/nmi/64: Switch stacks on userspace NMI entry
  x86/nmi/64: Remove asm code that saves CR2
  x86/nmi: Enable nested do_nmi() handling for 64-bit kernels
  Revert "iio: bmg160: IIO_BUFFER and IIO_TRIGGERED_BUFFER are required"
  net: gso: use feature flag argument in all protocol gso handlers
  bna: fix interrupts storm caused by erroneous packets
  udp: fix dst races with multicast early demux
  rds: fix an integer overflow test in rds_info_getsockopt()
  packet: missing dev_put() in packet_do_bind()
  fib_rules: fix fib rule dumps across multiple skbs
  openvswitch: Zero flows on allocation.
  sctp: fix race on protocol/netns initialization
  netlink, mmap: transform mmap skb into full skb on taps
  net/ipv6: Correct PIM6 mrt_lock handling
  ...

1 files changed, 41 insertions, 4 deletions

diff --git a/net/core/datagram.c b/net/core/datagram.c
index a16ed7bbe376..13bc7dad7990 100644
--- a/net/core/datagram.c
+++ b/net/core/datagram.c
@@ -130,6 +130,35 @@ out_noerr:
 	goto out;
 }
 
+static struct sk_buff *skb_set_peeked(struct sk_buff *skb)
+{
+	struct sk_buff *nskb;
+
+	if (skb->peeked)
+		return skb;
+
+	/* We have to unshare an skb before modifying it. */
+	if (!skb_shared(skb))
+		goto done;
+
+	nskb = skb_clone(skb, GFP_ATOMIC);
+	if (!nskb)
+		return ERR_PTR(-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 skb;
+}
+
 /**
  *	__skb_recv_datagram - Receive a datagram skbuff
  *	@sk: socket
@@ -164,7 +193,9 @@ out_noerr:
 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()
@@ -183,8 +214,6 @@ 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;
@@ -198,7 +227,12 @@ struct sk_buff *__skb_recv_datagram(struct sock *sk, unsigned int flags,
 					_off -= skb->len;
 					continue;
 				}
-				skb->peeked = 1;
+
+				skb = skb_set_peeked(skb);
+				error = PTR_ERR(skb);
+				if (IS_ERR(skb))
+					goto unlock_err;
+
 				atomic_inc(&skb->users);
 			} else
 				__skb_unlink(skb, queue);
@@ -222,6 +256,8 @@ 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;
@@ -742,7 +778,8 @@ __sum16 __skb_checksum_complete_head(struct sk_buff *skb, int len)
 	if (likely(!sum)) {
 		if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE))
 			netdev_rx_csum_fault(skb->dev);
-		skb->ip_summed = CHECKSUM_UNNECESSARY;
+		if (!skb_shared(skb))
+			skb->ip_summed = CHECKSUM_UNNECESSARY;
 	}
 	return sum;
 }