af_unix: fix bug on large send()

commit e370a723632 ("af_unix: improve STREAM behavior with fragmented
memory") added a bug on large send() because the
skb_copy_datagram_from_iovec() call always start from the beginning
of iovec.

We must instead use the @sent variable to properly skip the
already processed part.

Reported-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 1 deletions

diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index fee9e3397cd1..86de99ad2976 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -1669,7 +1669,8 @@ static int unix_stream_sendmsg(struct kiocb *kiocb, struct socket *sock,
                 skb_put(skb, size - data_len);
                 skb->data_len = data_len;
                 skb->len = size;
-                err = skb_copy_datagram_from_iovec(skb, 0, msg->msg_iov, 0, size);
+                err = skb_copy_datagram_from_iovec(skb, 0, msg->msg_iov,
+                                                   sent, size);
                 if (err) {
                         kfree_skb(skb);
                         goto out_err;