Re: [PATCH net] macvtap: fix recovery from gup errors

From: Jason Wang
Date: Sun Jun 23 2013 - 23:23:38 EST


On 06/23/2013 10:26 PM, Michael S. Tsirkin wrote:
> get user pages might fail partially in macvtap zero copy
> mode. To recover we need to put all pages that we got,
> but code used a wrong index resulting in double-free
> errors.
>
> Reported-by: Brad Hubbard <bhubbard@xxxxxxxxxx>
> Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
> ---
>
> Same as the tun patch really. Also stable material.

Acked-by: Jason Wang <jasowang@xxxxxxxxxx>
>
> drivers/net/macvtap.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c
> index 59e9605..4ddd108 100644
> --- a/drivers/net/macvtap.c
> +++ b/drivers/net/macvtap.c
> @@ -524,8 +524,9 @@ static int zerocopy_sg_from_iovec(struct sk_buff *skb, const struct iovec *from,
> return -EMSGSIZE;
> num_pages = get_user_pages_fast(base, size, 0, &page[i]);
> if (num_pages != size) {
> - for (i = 0; i < num_pages; i++)
> - put_page(page[i]);
> + int j;
> + for (j = 0; j < num_pages; j++)
> + put_page(page[i + j]);
> return -EFAULT;
> }
> truesize = size * PAGE_SIZE;

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/