On Fri, Dec 01, 2017 at 05:10:37AM -0500, w...@redhat.com wrote:
> From: Wei Xu <w...@redhat.com>
>
> tun_recvmsg() supports accepting skb by msg_control after
> commit ac77cfd4258f ("tun: support receiving skb through msg_control"),
> the skb if presented should be freed no matter how far it can go
> along, otherwise it would be leaked.
>
> This patch fixes several missed cases.
>
> Signed-off-by: Wei Xu <w...@redhat.com>
> Reported-by: Matthew Rosato <mjros...@linux.vnet.ibm.com>
Acked-by: Michael S. Tsirkin <m...@redhat.com>
> ---
> drivers/net/tun.c | 24 ++++++++++++++++++------
> 1 file changed, 18 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/net/tun.c b/drivers/net/tun.c
> index 9574900..4f4a842 100644
> --- a/drivers/net/tun.c
> +++ b/drivers/net/tun.c
> @@ -1952,8 +1952,11 @@ static ssize_t tun_do_read(struct tun_struct *tun,
> struct tun_file *tfile,
>
> tun_debug(KERN_INFO, tun, "tun_do_read\n");
>
> - if (!iov_iter_count(to))
> + if (!iov_iter_count(to)) {
> + if (skb)
> + kfree_skb(skb);
> return 0;
> + }
>
> if (!skb) {
> /* Read frames from ring */
> @@ -2069,22 +2072,24 @@ static int tun_recvmsg(struct socket *sock, struct
> msghdr *m, size_t total_len,
> {
> struct tun_file *tfile = container_of(sock, struct tun_file, socket);
> struct tun_struct *tun = tun_get(tfile);
> + struct sk_buff *skb = m->msg_control;
> int ret;
>
> - if (!tun)
> - return -EBADFD;
> + if (!tun) {
> + ret = -EBADFD;
> + goto out_free_skb;
> + }
>
> if (flags & ~(MSG_DONTWAIT|MSG_TRUNC|MSG_ERRQUEUE)) {
> ret = -EINVAL;
> - goto out;
> + goto out_put_tun;
> }
> if (flags & MSG_ERRQUEUE) {
> ret = sock_recv_errqueue(sock->sk, m, total_len,
> SOL_PACKET, TUN_TX_TIMESTAMP);
> goto out;
> }
> - ret = tun_do_read(tun, tfile, &m->msg_iter, flags & MSG_DONTWAIT,
> - m->msg_control);
> + ret = tun_do_read(tun, tfile, &m->msg_iter, flags & MSG_DONTWAIT, skb);
> if (ret > (ssize_t)total_len) {
> m->msg_flags |= MSG_TRUNC;
> ret = flags & MSG_TRUNC ? ret : total_len;
> @@ -2092,6 +2097,13 @@ static int tun_recvmsg(struct socket *sock, struct
> msghdr *m, size_t total_len,
> out:
> tun_put(tun);
> return ret;
> +
> +out_put_tun:
> + tun_put(tun);
> +out_free_skb:
> + if (skb)
> + kfree_skb(skb);
> + return ret;
> }
>
> static int tun_peek_len(struct socket *sock)
> --
> 1.8.3.1
