Re: [PATCH] accel/qaic: Fix integer overflow in qaic_validate_req()

[Dan Carpenter <dan.carpenter@linaro.org>]

On Thu, Mar 06, 2025 at 12:12:53PM -0700, Jeff Hugo wrote:
> On 3/5/2025 8:53 AM, Dan Carpenter wrote:
> > These are u64 variables that come from the user via
> > qaic_attach_slice_bo_ioctl().  Ensure that the math doesn't have an
> > integer wrapping bug.
> > 
> > Cc: stable@vger.kernel.org
> > Fixes: ff13be830333 ("accel/qaic: Add datapath")
> > Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
> > ---
> >   drivers/accel/qaic/qaic_data.c | 3 ++-
> >   1 file changed, 2 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/accel/qaic/qaic_data.c b/drivers/accel/qaic/qaic_data.c
> > index c20eb63750f5..cd5a31edba66 100644
> > --- a/drivers/accel/qaic/qaic_data.c
> > +++ b/drivers/accel/qaic/qaic_data.c
> > @@ -563,7 +563,8 @@ static int qaic_validate_req(struct qaic_device *qdev, struct qaic_attach_slice_
> >   		      invalid_sem(&slice_ent[i].sem2) || invalid_sem(&slice_ent[i].sem3))
> >   			return -EINVAL;
> > -		if (slice_ent[i].offset + slice_ent[i].size > total_size)
> > +		if (slice_ent[i].offset > U64_MAX - slice_ent[i].size ||
> > +		    slice_ent[i].offset + slice_ent[i].size > total_size)
> >   			return -EINVAL;
> >   	}
> 
> I agree this is an issue that needs to be addressed.  However, it seems that
> overflow checking helpers exist (include/linux/overflow.h), therefore open
> coding a check feels non-preferable.  I think check_add_overflow() would be
> the way to go.  Do you agree?

Sure.

regards,
dan carpenter