From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [140.186.70.92] (port=50887 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1OYQDp-000279-Mc for qemu-devel@nongnu.org; Mon, 12 Jul 2010 17:07:30 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.69) (envelope-from ) id 1OYQDj-0002Dk-Tt for qemu-devel@nongnu.org; Mon, 12 Jul 2010 17:07:29 -0400 Received: from mail-qw0-f45.google.com ([209.85.216.45]:49749) by eggs.gnu.org with esmtp (Exim 4.69) (envelope-from ) id 1OYQDj-0002Dd-Rn for qemu-devel@nongnu.org; Mon, 12 Jul 2010 17:07:23 -0400 Received: by qwf6 with SMTP id 6so725967qwf.4 for ; Mon, 12 Jul 2010 14:07:22 -0700 (PDT) Message-ID: <4C3B8409.9030202@codemonkey.ws> Date: Mon, 12 Jul 2010 16:07:21 -0500 From: Anthony Liguori MIME-Version: 1.0 References: <20100712174823.GA11411@redhat.com> In-Reply-To: <20100712174823.GA11411@redhat.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Subject: [Qemu-devel] Re: [PATCH RFC] e1000: fix access 4 bytes beyond buffer end List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Michael S. Tsirkin" Cc: alex.williamson@redhat.com, qemu-devel@nongnu.org On 07/12/2010 12:48 PM, Michael S. Tsirkin wrote: > We do range check for size, and get size as buffer, > but copy size + 4 bytes (4 is for FCS). > Let's copy size bytes but put size + 4 in length. > > Signed-off-by: Michael S. Tsirkin > I think I'd feel slightly better if we zero'd out the FCS before writing it to the guest. It is potentially a data leak. Regards, Anthony Liguori > --- > > Anthony, Alex, please review. > > hw/e1000.c | 3 +-- > 1 files changed, 1 insertions(+), 2 deletions(-) > > diff --git a/hw/e1000.c b/hw/e1000.c > index 0da65f9..70aba11 100644 > --- a/hw/e1000.c > +++ b/hw/e1000.c > @@ -649,7 +649,6 @@ e1000_receive(VLANClientState *nc, const uint8_t *buf, size_t size) > } > > rdh_start = s->mac_reg[RDH]; > - size += 4; // for the header > do { > if (s->mac_reg[RDH] == s->mac_reg[RDT]&& s->check_rxov) { > set_ics(s, 0, E1000_ICS_RXO); > @@ -663,7 +662,7 @@ e1000_receive(VLANClientState *nc, const uint8_t *buf, size_t size) > if (desc.buffer_addr) { > cpu_physical_memory_write(le64_to_cpu(desc.buffer_addr), > (void *)(buf + vlan_offset), size); > - desc.length = cpu_to_le16(size); > + desc.length = cpu_to_le16(size + 4 /* for FCS */); > desc.status |= E1000_RXD_STAT_EOP|E1000_RXD_STAT_IXSM; > } else // as per intel docs; skip descriptors with null buf addr > DBGOUT(RX, "Null RX descriptor!!\n"); >