From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [140.186.70.92] (port=36524 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1OYdTS-0003vK-ND for qemu-devel@nongnu.org; Tue, 13 Jul 2010 07:16:34 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.69) (envelope-from ) id 1OYdTR-0003LT-Fu for qemu-devel@nongnu.org; Tue, 13 Jul 2010 07:16:30 -0400 Received: from mx1.redhat.com ([209.132.183.28]:15307) by eggs.gnu.org with esmtp (Exim 4.69) (envelope-from ) id 1OYdTR-0003L6-9W for qemu-devel@nongnu.org; Tue, 13 Jul 2010 07:16:29 -0400 Date: Tue, 13 Jul 2010 14:11:10 +0300 From: "Michael S. Tsirkin" Subject: Re: [Qemu-devel] Re: [PATCH RFC] e1000: fix access 4 bytes beyond buffer end Message-ID: <20100713111110.GB3446@redhat.com> References: <20100712174823.GA11411@redhat.com> <4C3B8409.9030202@codemonkey.ws> <20100712224254.GD13707@redhat.com> <4C3B9E84.3050809@codemonkey.ws> <20100713063549.GA5463@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100713063549.GA5463@redhat.com> List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Gleb Natapov Cc: alex.williamson@redhat.com, qemu-devel@nongnu.org On Tue, Jul 13, 2010 at 09:35:49AM +0300, Gleb Natapov wrote: > On Mon, Jul 12, 2010 at 06:00:20PM -0500, Anthony Liguori wrote: > > On 07/12/2010 05:42 PM, Michael S. Tsirkin wrote: > > >On Mon, Jul 12, 2010 at 04:07:21PM -0500, Anthony Liguori wrote: > > >>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 > > >I am guessing there's no chance guest actually looks > > >at this data, otherwise it won't match and we'd get errors, right? > > > > That's my assumption too. Although I believe there are some known > > issues with e1000 and certain versions of Windows and the Microsoft > > built-in driver. Maybe this is why those drivers don't work and the > > Intel drivers do? > > > At least one known issue with Windows drivers to me is that they > sometimes (on resume from S4 at least) enable interrupts before setup > irq routing, so if interrupt is generated in the wrong time it hangs the > guest. I guess it works on real HW for them because line speed > negotiation takes non-zero time. I guess we could work around this. Is there a bz? > > 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"); > > > > -- > Gleb.