On Fri, 22 Sep 2017, Dan Carpenter wrote:
> There used to be an integer overflow check in proc_do_submiturb() but
> we removed it. It turns out that it's still required. The
> uurb->buffer_length variable is a signed integer and it's controlled by
> the user. It can lead to an integer overflow when we do:
>
> num_sgs = DIV_ROUND_UP(uurb->buffer_length, USB_SG_SIZE);
>
> If we strip away the macro then that line looks like this:
>
> num_sgs = (uurb->buffer_length + USB_SG_SIZE - 1) / USB_SG_SIZE;
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> It's the first addition which can overflow.
>
> Fixes: 1129d270cbfb ("USB: Increase usbfs transfer limit")
> Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
> ---
> v2: Cast the ->buffer_length to unsigned int which is more readable than
> relying on type promotion.
For both 1/2 and 2/2:
Acked-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
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