From mboxrd@z Thu Jan 1 00:00:00 1970 From: shawn.guo@freescale.com (Shawn Guo) Date: Thu, 30 Dec 2010 10:12:44 +0800 Subject: [PATCH 03/10] net/fec: add mac field into platform data and consolidate fec_get_mac In-Reply-To: <20101229124220.GD14221@pengutronix.de> References: <1293548155-16328-1-git-send-email-shawn.guo@freescale.com> <1293548155-16328-4-git-send-email-shawn.guo@freescale.com> <20101229065329.GB31010@jasper.tkos.co.il> <20101229100520.GB19347@freescale.com> <20101229103138.GT14221@pengutronix.de> <20101229115808.GF19347@freescale.com> <20101229124220.GD14221@pengutronix.de> Message-ID: <20101230021243.GA20155@freescale.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hi Uwe, On Wed, Dec 29, 2010 at 01:42:21PM +0100, Uwe Kleine-K?nig wrote: > Hello Shawn, > > On Wed, Dec 29, 2010 at 07:58:09PM +0800, Shawn Guo wrote: > > On Wed, Dec 29, 2010 at 11:31:38AM +0100, Uwe Kleine-K?nig wrote: > > > On Wed, Dec 29, 2010 at 06:05:21PM +0800, Shawn Guo wrote: > > > > On Wed, Dec 29, 2010 at 08:53:30AM +0200, Baruch Siach wrote: > > > > if (iap == fec_mac_default) > > > > dev->dev_addr[ETH_ALEN-1] = fec_mac_default[ETH_ALEN-1] + fep->pdev->id; > > > Can this overflow? (I didn't check the code, so my concern might be > > > completely stupid here.) > > No. dev->dev_addr points to netdev_hw_addr->addr, which is a 32 bytes array. > I didn't mean an out-of-bound access, but what is if > fec_mac_default[ETH_ALEN-1] is 0xff and you add 1? Does that result in > 0x100 or 0? What if id is <0? For big ids you might even handle a > carry to indixes First of all, all my patch did is changing fep->index to, fep->pdev->id, which should not bring any problem you are concerned. Secondly, I do not understand how the overflow on fec_mac_default[ETH_ALEN-1] can result in a carry on the next array element. Here is what I'm seeing with fec_mac=00:04:9f:01:30:ff. eth0 Link encap:Ethernet HWaddr 00:04:9F:01:30:FF eth1 Link encap:Ethernet HWaddr 00:04:9F:01:30:00 -- Regards, Shawn