On Tue, Sep 27, 2011 at 02:20:29PM +0300, Sasha Levin wrote:
> On Tue, 2011-09-27 at 10:00 +0300, Michael S. Tsirkin wrote:
> > > skb = page_to_skb(vi, page, len);
> > > ...
> >
> > Sorry I don't get it yet. Where is mergeable ignored here?
>
> The NULL deref happens in page_to_skb(), before merge buffers are
> handled.
The len here is a single buffer length, so for mergeable
buffers it is <= the size of the buffer we gave to hardware,
which is PAGE_SIZE.
err = virtqueue_add_buf_single(vi->rvq, page_address(page),
PAGE_SIZE, false, page, gfp);
Unless of course we are trying to work around broken hardware again,
which I don't have a problem with, but should probably
get appropriate comments in code and trigger a warning.
> I'll test it and see if it's really the case.
>
> --
>
> Sasha.
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