From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([2001:4830:134:3::10]:50721)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <mst@redhat.com>) id 1a3Lyz-0005bK-D0
	for qemu-devel@nongnu.org; Mon, 30 Nov 2015 05:46:58 -0500
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <mst@redhat.com>) id 1a3Lyu-0005aA-T0
	for qemu-devel@nongnu.org; Mon, 30 Nov 2015 05:46:57 -0500
Date: Mon, 30 Nov 2015 12:46:49 +0200
From: "Michael S. Tsirkin" <mst@redhat.com>
Message-ID: <20151130124642-mutt-send-email-mst@redhat.com>
References: <1448869103-16281-1-git-send-email-jasowang@redhat.com>
	<1448869103-16281-2-git-send-email-jasowang@redhat.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <1448869103-16281-2-git-send-email-jasowang@redhat.com>
Subject: Re: [Qemu-devel] [PATCH for 2.5 2/2] pcnet: fix rx buffer
	overflow(CVE-2015-7512)
List-Id: <qemu-devel.nongnu.org>
List-Unsubscribe: <https://lists.nongnu.org/mailman/options/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.nongnu.org/archive/html/qemu-devel>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <https://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: Jason Wang <jasowang@redhat.com>
Cc: qemu-stable@nongnu.org, qemu-devel@nongnu.org, Prasad J Pandit <pjp@fedoraproject.org>

On Mon, Nov 30, 2015 at 03:38:23PM +0800, Jason Wang wrote:
> Backends could provide a packet whose length is greater than buffer
> size. Check for this and truncate the packet to avoid rx buffer
> overflow in this case.
> 
> Cc: Prasad J Pandit <pjp@fedoraproject.org>
> Cc: qemu-stable@nongnu.org
> Signed-off-by: Jason Wang <jasowang@redhat.com>

Reviewed-by: Michael S. Tsirkin <mst@redhat.com>

> ---
>  hw/net/pcnet.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/hw/net/pcnet.c b/hw/net/pcnet.c
> index 309c40b..1f4a3db 100644
> --- a/hw/net/pcnet.c
> +++ b/hw/net/pcnet.c
> @@ -1064,6 +1064,12 @@ ssize_t pcnet_receive(NetClientState *nc, const uint8_t *buf, size_t size_)
>              int pktcount = 0;
>  
>              if (!s->looptest) {
> +                if (size > 4092) {
> +#ifdef PCNET_DEBUG_RMD
> +                    fprintf(stderr, "pcnet: truncates rx packet.\n");
> +#endif
> +                    size = 4092;
> +                }
>                  memcpy(src, buf, size);
>                  /* no need to compute the CRC */
>                  src[size] = 0;
> -- 
> 2.5.0
>