releases/4.14.7/tap-free-skb-if-flags-error.patch

   1 From foo@baz Thu Dec 14 11:45:40 CET 2017
   2 From: Wei Xu <wexu@redhat.com>
   3 Date: Fri, 1 Dec 2017 05:10:38 -0500
   4 Subject: tap: free skb if flags error
   5
   6 From: Wei Xu <wexu@redhat.com>
   7
   8
   9 [ Upstream commit 61d78537843e676e7f56ac6db333db0c0529b892 ]
  10
  11 tap_recvmsg() supports accepting skb by msg_control after
  12 commit 3b4ba04acca8 ("tap: support receiving skb from msg_control"),
  13 the skb if presented should be freed within the function, otherwise
  14 it would be leaked.
  15
  16 Signed-off-by: Wei Xu <wexu@redhat.com>
  17 Reported-by: Matthew Rosato <mjrosato@linux.vnet.ibm.com>
  18 Acked-by: Michael S. Tsirkin <mst@redhat.com>
  19 Signed-off-by: David S. Miller <davem@davemloft.net>
  20 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  21 ---
  22  drivers/net/tap.c |   14 ++++++++++----
  23  1 file changed, 10 insertions(+), 4 deletions(-)
  24
  25 --- a/drivers/net/tap.c
  26 +++ b/drivers/net/tap.c
  27 @@ -829,8 +829,11 @@ static ssize_t tap_do_read(struct tap_qu
  28         DEFINE_WAIT(wait);
  29         ssize_t ret = 0;
  30
  31 -       if (!iov_iter_count(to))
  32 +       if (!iov_iter_count(to)) {
  33 +               if (skb)
  34 +                       kfree_skb(skb);
  35                 return 0;
  36 +       }
  37
  38         if (skb)
  39                 goto put;
  40 @@ -1154,11 +1157,14 @@ static int tap_recvmsg(struct socket *so
  41                        size_t total_len, int flags)
  42  {
  43         struct tap_queue *q = container_of(sock, struct tap_queue, sock);
  44 +       struct sk_buff *skb = m->msg_control;
  45         int ret;
  46 -       if (flags & ~(MSG_DONTWAIT|MSG_TRUNC))
  47 +       if (flags & ~(MSG_DONTWAIT|MSG_TRUNC)) {
  48 +               if (skb)
  49 +                       kfree_skb(skb);
  50                 return -EINVAL;
  51 -       ret = tap_do_read(q, &m->msg_iter, flags & MSG_DONTWAIT,
  52 -                         m->msg_control);
  53 +       }
  54 +       ret = tap_do_read(q, &m->msg_iter, flags & MSG_DONTWAIT, skb);
  55         if (ret > total_len) {
  56                 m->msg_flags |= MSG_TRUNC;
  57                 ret = flags & MSG_TRUNC ? ret : total_len;