tun: fix tun_chr_aio_read so that aio works

aio_read gets const struct iovec * but tun_chr_aio_read casts this to struct
iovec * and modifies the iovec. As a result, attempts to use io_submit
to get packets from a tun device fail with weird errors such as EINVAL.

Fix by using the new skb_copy_datagram_const_iovec.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 735bf41..3b513e2 100644 (file)
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -683,7 +683,7 @@ static ssize_t tun_chr_aio_write(struct kiocb *iocb, const struct iovec *iv,
 /* Put packet to the user space buffer */
 static __inline__ ssize_t tun_put_user(struct tun_struct *tun,
                                       struct sk_buff *skb,
-                                      struct iovec *iv, int len)
+                                      const struct iovec *iv, int len)
 {
        struct tun_pi pi = { 0, skb->protocol };
        ssize_t total = 0;
@@ -697,7 +697,7 @@ static __inline__ ssize_t tun_put_user(struct tun_struct *tun,
                        pi.flags |= TUN_PKT_STRIP;
                }
 
-               if (memcpy_toiovec(iv, (void *) &pi, sizeof(pi)))
+               if (memcpy_toiovecend(iv, (void *) &pi, 0, sizeof(pi)))
                        return -EFAULT;
                total += sizeof(pi);
        }
@@ -730,14 +730,15 @@ static __inline__ ssize_t tun_put_user(struct tun_struct *tun,
                        gso.csum_offset = skb->csum_offset;
                } /* else everything is zero */
 
-               if (unlikely(memcpy_toiovec(iv, (void *)&gso, sizeof(gso))))
+               if (unlikely(memcpy_toiovecend(iv, (void *)&gso, total,
+                                              sizeof(gso))))
                        return -EFAULT;
                total += sizeof(gso);
        }
 
        len = min_t(int, skb->len, len);
 
-       skb_copy_datagram_iovec(skb, 0, iv, len);
+       skb_copy_datagram_const_iovec(skb, 0, iv, total, len);
        total += len;
 
        tun->dev->stats.tx_packets++;
@@ -792,7 +793,7 @@ static ssize_t tun_chr_aio_read(struct kiocb *iocb, const struct iovec *iv,
                }
                netif_wake_queue(tun->dev);
 
-               ret = tun_put_user(tun, skb, (struct iovec *) iv, len);
+               ret = tun_put_user(tun, skb, iv, len);
                kfree_skb(skb);
                break;
        }