Re: [PATCH] macvtap: fix the uninitialized var using inmacvtap_alloc_skb()

From: Ian Campbell
Date: Tue Sep 20 2011 - 06:58:08 EST


On Mon, 2011-09-19 at 12:54 +0300, Michael S. Tsirkin wrote:
> On Mon, Sep 19, 2011 at 05:48:31PM +0800, Jason Wang wrote:
> > Commit d1b08284 use new frag API but would leave f to be used
> > uninitialized, this patch fix it.
> >
> > Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
>
> Good catch. Makes absolute sense.
>
> Acked-by: Michael S. Tsirkin <mst@xxxxxxxxxx>

Agreed. I like this one better than the one I just sent out so:

Acked-by: Ian Campbell <ian.campbell@xxxxxxxxxx>

Thanks Jason.

>
> > ---
> > drivers/net/macvtap.c | 12 +++++-------
> > 1 files changed, 5 insertions(+), 7 deletions(-)
> >
> > diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c
> > index 7c3f84a..3da5578 100644
> > --- a/drivers/net/macvtap.c
> > +++ b/drivers/net/macvtap.c
> > @@ -453,7 +453,6 @@ static int zerocopy_sg_from_iovec(struct sk_buff *skb, const struct iovec *from,
> > int copy = skb_headlen(skb);
> > int size, offset1 = 0;
> > int i = 0;
> > - skb_frag_t *f;
> >
> > /* Skip over from offset */
> > while (count && (offset >= from->iov_len)) {
> > @@ -503,14 +502,13 @@ static int zerocopy_sg_from_iovec(struct sk_buff *skb, const struct iovec *from,
> > skb->truesize += len;
> > atomic_add(len, &skb->sk->sk_wmem_alloc);
> > while (len) {
> > - __skb_fill_page_desc(
> > - skb, i, page[i],
> > - base & ~PAGE_MASK,
> > - min_t(int, len, PAGE_SIZE - f->page_offset));
> > + int off = base & ~PAGE_MASK;
> > + int size = min_t(int, len, PAGE_SIZE - off);
> > + __skb_fill_page_desc(skb, i, page[i], off, size);
> > skb_shinfo(skb)->nr_frags++;
> > /* increase sk_wmem_alloc */
> > - base += f->size;
> > - len -= f->size;
> > + base += size;
> > + len -= size;
> > i++;
> > }
> > offset1 = 0;
> --
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