1 files changed, 6 insertions, 7 deletions

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index e61f7cd65d08..5fdcb8d108d4 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -1182,13 +1182,13 @@ out:
  *      @sk: socket
  *
  *      Drops all bad checksum frames, until a valid one is found.
- *      Returns the length of found skb, or 0 if none is found.
+ *      Returns the length of found skb, or -1 if none is found.
  */
-static unsigned int first_packet_length(struct sock *sk)
+static int first_packet_length(struct sock *sk)
 {
         struct sk_buff_head list_kill, *rcvq = &sk->sk_receive_queue;
         struct sk_buff *skb;
-        unsigned int res;
+        int res;
 
         __skb_queue_head_init(&list_kill);
 
@@ -1203,7 +1203,7 @@ static unsigned int first_packet_length(struct sock *sk)
                 __skb_unlink(skb, rcvq);
                 __skb_queue_tail(&list_kill, skb);
         }
-        res = skb ? skb->len : 0;
+        res = skb ? skb->len : -1;
         spin_unlock_bh(&rcvq->lock);
 
         if (!skb_queue_empty(&list_kill)) {
@@ -1232,7 +1232,7 @@ int udp_ioctl(struct sock *sk, int cmd, unsigned long arg)
 
         case SIOCINQ:
         {
-                unsigned int amount = first_packet_length(sk);
+                int amount = max_t(int, 0, first_packet_length(sk));
 
                 return put_user(amount, (int __user *)arg);
         }
@@ -2184,7 +2184,7 @@ unsigned int udp_poll(struct file *file, struct socket *sock, poll_table *wait)
 
         /* Check for false positives due to checksum errors */
         if ((mask & POLLRDNORM) && !(file->f_flags & O_NONBLOCK) &&
-            !(sk->sk_shutdown & RCV_SHUTDOWN) && !first_packet_length(sk))
+            !(sk->sk_shutdown & RCV_SHUTDOWN) && first_packet_length(sk) == -1)
                 mask &= ~(POLLIN | POLLRDNORM);
 
         return mask;
@@ -2216,7 +2216,6 @@ struct proto udp_prot = {
         .sysctl_wmem       = &sysctl_udp_wmem_min,
         .sysctl_rmem       = &sysctl_udp_rmem_min,
         .obj_size          = sizeof(struct udp_sock),
-        .slab_flags        = SLAB_DESTROY_BY_RCU,
         .h.udp_table       = &udp_table,
 #ifdef CONFIG_COMPAT
         .compat_setsockopt = compat_udp_setsockopt,