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

[Jeff Hugo <jeff.hugo@oss.qualcomm.com>]

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?

-Jeff