On Mon, Mar 01, 2021 at 12:12:34PM +0200, Eran Ben Elisha wrote:
>
>
> On 2/19/2021 11:57 AM, Dan Carpenter wrote:
> > The value of "sec" comes from the user. Negative values will lead to
> > shift wrapping inside the perout_conf_real_time() function and triggger
> > a UBSan warning.
> >
> > Add a check and return -EINVAL to prevent that from happening.
> >
> > Fixes: 432119de33d9 ("net/mlx5: Add cyc2time HW translation mode support")
> > Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
> > ---
> > Saeed, I think this goes through your git tree and you will send a pull
> > request to the networking?
> >
> > From static analysis. Not tested.
> >
> > drivers/net/ethernet/mellanox/mlx5/core/lib/clock.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/net/ethernet/mellanox/mlx5/core/lib/clock.c b/drivers/net/ethernet/mellanox/mlx5/core/lib/clock.c
> > index b0e129d0f6d8..286824ca62b5 100644
> > --- a/drivers/net/ethernet/mellanox/mlx5/core/lib/clock.c
> > +++ b/drivers/net/ethernet/mellanox/mlx5/core/lib/clock.c
> > @@ -516,7 +516,7 @@ static int mlx5_perout_configure(struct ptp_clock_info *ptp,
> > nsec = rq->perout.start.nsec;
> > sec = rq->perout.start.sec;
> > - if (rt_mode && sec > U32_MAX)
>
> This if clause was set to reject perout time start sec bigger than U32_MAX,
> as rt mode specifically doesn't support it.
>
> A user negative values protection should be generic for all netdev drivers,
> inside the caller ioctl func, and not part of any driver code.
>
I'm not a networking expert... :/ It's easier for me to see that this
code will trigger a syzbot splat vs saying that there is no valid use
case for negative seconds any driver.
What you're saying sounds reasonable enough to me, but I don't know
enough about networking to comment one way or the other. Maybe the
other drivers have a use for negative seconds?
regards,
dan carpenter
> > + if (rt_mode && (sec < 0 || sec > U32_MAX))
> > return -EINVAL;
> > time_stamp = rt_mode ? perout_conf_real_time(sec, nsec) :
> >
