Re: [PATCH v2 1/4] can: kvaser_usb: Don't free packets when tight on URBs

Ahmed S. Darwish
2014-12-25T09:39:12Z

On Wed, Dec 24, 2014 at 06:50:11PM -0800, Greg KH wrote:
> On Thu, Dec 25, 2014 at 01:56:44AM +0200, Ahmed S. Darwish wrote:
> > From: Ahmed S. Darwish <ahmed.darwish@valeo.com>
> >
> > Flooding the Kvaser CAN to USB dongle with multiple reads and
> > writes in high frequency caused seemingly-random panics in the
> > kernel.
> >
> > On further inspection, it seems the driver erroneously freed the
> > to-be-transmitted packet upon getting tight on URBs and returning
> > NETDEV_TX_BUSY, leading to invalid memory writes and double frees
> > at a later point in time.
> >
> > Note:
> >
> > Finding no more URBs/transmit-contexts and returning NETDEV_TX_BUSY
> > is a driver bug in and out of itself: it means that our start/stop
> > queue flow control is broken.
> >
> > This patch only fixes the (buggy) error handling code; the root
> > cause shall be fixed in a later commit.
> >
> > Signed-off-by: Ahmed S. Darwish <ahmed.darwish@valeo.com>
> > ---
> > drivers/net/can/usb/kvaser_usb.c | 12 ++++++------
> > 1 file changed, 6 insertions(+), 6 deletions(-)
> >
> > (Marc, Greg, I believe this should also be added to -stable?)
>
>
> <formletter>
>
> This is not the correct way to submit patches for inclusion in the
> stable kernel tree. Please read Documentation/stable_kernel_rules.txt
> for how to do this properly.
>
> </formletter>

<msg-response>

Note taken. Sorry about that ;-)

</msg-response>