4 files changed, 18 insertions, 13 deletions

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 2b7317ff297f..f3cf43de3c2a 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -2046,7 +2046,7 @@ static inline void skb_frag_add_head(struct sk_buff *skb, struct sk_buff *frag)
         for (iter = skb_shinfo(skb)->frag_list; iter; iter = iter->next)
 
 extern struct sk_buff *__skb_recv_datagram(struct sock *sk, unsigned flags,
-                                           int *peeked, int *err);
+                                           int *peeked, int *off, int *err);
 extern struct sk_buff *skb_recv_datagram(struct sock *sk, unsigned flags,
                                          int noblock, int *err);
 extern unsigned int    datagram_poll(struct file *file, struct socket *sock,
diff --git a/net/core/datagram.c b/net/core/datagram.c
index 6f54d0a17f8e..d3cf12f62c8f 100644
--- a/net/core/datagram.c
+++ b/net/core/datagram.c
@@ -132,6 +132,8 @@ out_noerr:
  *      __skb_recv_datagram - Receive a datagram skbuff
  *      @sk: socket
  *      @flags: MSG_ flags
+ *      @off: an offset in bytes to peek skb from. Returns an offset
+ *            within an skb where data actually starts
  *      @peeked: returns non-zero if this packet has been seen before
  *      @err: error code returned
  *
@@ -158,7 +160,7 @@ out_noerr:
  *      the standard around please.
  */
 struct sk_buff *__skb_recv_datagram(struct sock *sk, unsigned flags,
-                                    int *peeked, int *err)
+                                    int *peeked, int *off, int *err)
 {
         struct sk_buff *skb;
         long timeo;
@@ -183,19 +185,22 @@ struct sk_buff *__skb_recv_datagram(struct sock *sk, unsigned flags,
                 struct sk_buff_head *queue = &sk->sk_receive_queue;
 
                 spin_lock_irqsave(&queue->lock, cpu_flags);
-                skb = skb_peek(queue);
-                if (skb) {
+                skb_queue_walk(queue, skb) {
                         *peeked = skb->peeked;
                         if (flags & MSG_PEEK) {
+                                if (*off >= skb->len) {
+                                        *off -= skb->len;
+                                        continue;
+                                }
                                 skb->peeked = 1;
                                 atomic_inc(&skb->users);
                         } else
                                 __skb_unlink(skb, queue);
-                }
-                spin_unlock_irqrestore(&queue->lock, cpu_flags);
 
-                if (skb)
+                        spin_unlock_irqrestore(&queue->lock, cpu_flags);
                         return skb;
+                }
+                spin_unlock_irqrestore(&queue->lock, cpu_flags);
 
                 /* User doesn't want to wait */
                 error = -EAGAIN;
@@ -215,10 +220,10 @@ EXPORT_SYMBOL(__skb_recv_datagram);
 struct sk_buff *skb_recv_datagram(struct sock *sk, unsigned flags,
                                   int noblock, int *err)
 {
-        int peeked;
+        int peeked, off = 0;
 
         return __skb_recv_datagram(sk, flags | (noblock ? MSG_DONTWAIT : 0),
-                                   &peeked, err);
+                                   &peeked, &off, err);
 }
 EXPORT_SYMBOL(skb_recv_datagram);
 
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index cd99f1a0f59f..7c41ab84e72e 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -1167,7 +1167,7 @@ int udp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
         struct sockaddr_in *sin = (struct sockaddr_in *)msg->msg_name;
         struct sk_buff *skb;
         unsigned int ulen, copied;
-        int peeked;
+        int peeked, off = 0;
         int err;
         int is_udplite = IS_UDPLITE(sk);
         bool slow;
@@ -1183,7 +1183,7 @@ int udp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
 
 try_again:
         skb = __skb_recv_datagram(sk, flags | (noblock ? MSG_DONTWAIT : 0),
-                                  &peeked, &err);
+                                  &peeked, &off, &err);
         if (!skb)
                 goto out;
 
diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 8aebf8f90436..37b0699e95e5 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -342,7 +342,7 @@ int udpv6_recvmsg(struct kiocb *iocb, struct sock *sk,
         struct inet_sock *inet = inet_sk(sk);
         struct sk_buff *skb;
         unsigned int ulen, copied;
-        int peeked;
+        int peeked, off = 0;
         int err;
         int is_udplite = IS_UDPLITE(sk);
         int is_udp4;
@@ -359,7 +359,7 @@ int udpv6_recvmsg(struct kiocb *iocb, struct sock *sk,
 
 try_again:
         skb = __skb_recv_datagram(sk, flags | (noblock ? MSG_DONTWAIT : 0),
-                                  &peeked, &err);
+                                  &peeked, &off, &err);
         if (!skb)
                 goto out;