On Sun, Jun 23, 2013 at 07:36:21PM +0400, Sergei Shtylyov wrote:
> Hello.
>
> On 23-06-2013 18:19, Michael S. Tsirkin wrote:
>
> >get user pages might fail partially in tun 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 <bhubb...@redhat.com>
> >Signed-off-by: Michael S. Tsirkin <m...@redhat.com>
> >---
>
> >I haven't figured out why do we get failures,
> >but recovery is clearly wrong.
>
> >This is also -stable material.
>
> > drivers/net/tun.c | 5 +++--
> > 1 file changed, 3 insertions(+), 2 deletions(-)
>
> >diff --git a/drivers/net/tun.c b/drivers/net/tun.c
> >index bfa9bb4..c098b1e 100644
> >--- a/drivers/net/tun.c
> >+++ b/drivers/net/tun.c
> >@@ -1010,8 +1010,9 @@ 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;
>
> Empty line wouldn't hurt here, after declaration.
>
> >+ for (j = 0; j < num_pages; j++)
> >+ put_page(page[i + j]);
I think it's clearer without: this is the only code
within this block, declaration is really part of
the loop that comes after it.
An empty line would break it up visually.
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