From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Hildenbrand Subject: Re: [PATCH] virtio_balloon: prevent pfn array overflow Date: Thu, 6 Feb 2020 09:29:27 +0100 Message-ID: <7ccd0cff-b132-aa90-7117-5058df29810f@redhat.com> References: <20200206074644.1177551-1-mst@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20200206074644.1177551-1-mst@redhat.com> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: "Michael S. Tsirkin" , linux-kernel@vger.kernel.org Cc: Jason Wang , virtualization@lists.linux-foundation.org, linux-mm@kvack.org List-Id: virtualization@lists.linuxfoundation.org On 06.02.20 08:47, Michael S. Tsirkin wrote: > Make sure, at build time, that pfn array is big enough to hold a single > page. It happens to be true since the PAGE_SHIFT value at the moment is > 20, which is 1M - exactly 256 4K balloon pages. > > Signed-off-by: Michael S. Tsirkin > --- > drivers/virtio/virtio_balloon.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c > index 8e400ece9273..2457c54b6185 100644 > --- a/drivers/virtio/virtio_balloon.c > +++ b/drivers/virtio/virtio_balloon.c > @@ -158,6 +158,8 @@ static void set_page_pfns(struct virtio_balloon *vb, > { > unsigned int i; > > + BUILD_BUG_ON(VIRTIO_BALLOON_PAGES_PER_PAGE > VIRTIO_BALLOON_ARRAY_PFNS_MAX); > + > /* > * Set balloon pfns pointing at this page. > * Note that the first pfn points at start of the page. > Reviewed-by: David Hildenbrand -- Thanks, David / dhildenb