From: "Michael S. Tsirkin" <mst@redhat.com>
To: Sasha Levin <levinsasha928@gmail.com>
Cc: linux-kernel@vger.kernel.org,
Rusty Russell <rusty@rustcorp.com.au>,
virtualization@lists.linux-foundation.org,
netdev@vger.kernel.org, kvm@vger.kernel.org
Subject: Re: [PATCH 1/2] virtio-net: Verify page list size before fitting into skb
Date: Tue, 27 Sep 2011 15:37:20 +0300 [thread overview]
Message-ID: <20110927123719.GB11276@redhat.com> (raw)
In-Reply-To: <1317122429.3467.5.camel@lappy>
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.
next prev parent reply other threads:[~2011-09-27 12:37 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-09-26 17:41 [PATCH 1/2] virtio-net: Verify page list size before fitting into skb Sasha Levin
2011-09-26 17:41 ` [PATCH 2/2] virtio-net: Prevent NULL dereference Sasha Levin
2011-09-26 18:47 ` Michael S. Tsirkin
2011-09-26 18:44 ` [PATCH 1/2] virtio-net: Verify page list size before fitting into skb Michael S. Tsirkin
2011-09-26 19:37 ` Sasha Levin
2011-09-26 19:45 ` Pekka Enberg
2011-09-26 19:57 ` Michael S. Tsirkin
2011-09-26 20:04 ` Pekka Enberg
2011-09-26 19:57 ` Sasha Levin
2011-09-26 19:55 ` Michael S. Tsirkin
2011-09-27 6:44 ` Sasha Levin
2011-09-27 7:00 ` Michael S. Tsirkin
2011-09-27 11:20 ` Sasha Levin
2011-09-27 12:37 ` Michael S. Tsirkin [this message]
2011-09-28 12:19 ` Sasha Levin
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