From mboxrd@z Thu Jan 1 00:00:00 1970 From: Toby Gray Subject: Re: [PATCH 4/5] usb: usbnet: Add validation of dev->maxpacket to usbnet Date: Thu, 16 Feb 2012 10:55:05 +0000 Message-ID: <4F3CE089.5000105@realvnc.com> References: <1329317261-3406-1-git-send-email-toby.gray@realvnc.com> <1329317261-3406-5-git-send-email-toby.gray@realvnc.com> <201202152034.03000.oliver@neukum.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15; format=flowed Content-Transfer-Encoding: 7bit Cc: linux-usb-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, netdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Oliver Neukum Return-path: In-Reply-To: <201202152034.03000.oliver-GvhC2dPhHPQdnm+yROfE0A@public.gmane.org> Sender: linux-usb-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: netdev.vger.kernel.org On 15/02/12 19:34, Oliver Neukum wrote: > Am Mittwoch, 15. Februar 2012, 15:47:40 schrieb Toby Gray: >> Several parts of usbnet rely on dev->maxpacket not being set to 0 to >> prevent division by zero errors. >> >> This adds validation of the dev->maxpacket value being non-zero before >> treating the device probe as successful. >> >> Signed-off-by: Toby Gray >> --- >> drivers/net/usb/usbnet.c | 4 ++++ >> 1 files changed, 4 insertions(+), 0 deletions(-) >> >> diff --git a/drivers/net/usb/usbnet.c b/drivers/net/usb/usbnet.c >> index 4ccd316..1491c90 100644 >> --- a/drivers/net/usb/usbnet.c >> +++ b/drivers/net/usb/usbnet.c >> @@ -1427,6 +1427,10 @@ usbnet_probe (struct usb_interface *udev, const struct usb_device_id *prod) >> dev->rx_urb_size = dev->hard_mtu; >> if (!dev->maxpacket) >> dev->maxpacket = usb_maxpacket(dev->udev, dev->out, 1); >> + if (!dev->maxpacket) { >> + status = -ENODEV; >> + goto out3; > Hm. I am sceptical. If this happens a subdriver is buggy. We should > not hide that. I am afraid I have to reject this patch. That's understandable, I almost didn't include it in the series. The only reason I added this to the patch series was because I spent a while trying to track down a division by zero, when it turns out it was actually due to dev->maxpacket being zero when usbnet_start_xmit tried to calculate length % dev->maxpacket. Would you prefer that I drop this patch entirely or just change it to something like a BUG_ON? Regards, Toby -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html