On Sat, Sep 30, 2017 at 1:15 AM, Dan Carpenter <dan.carpenter@xxxxxxxxxx> wrote:
> There used to be a test against "if (param->sglen > MAX_SGLEN)" but it
> was removed during a refactor. It leads to an integer overflow and a
> stack overflow in test_queue() if we try to create a too large urbs[]
> array on the stack.
>
> There is a second integer overflow in test_queue() as well if
> "param->iterations" is too high. I don't immediately see that it's
> harmful but I've added a check to prevent it and silence the static
> checker warning.
>
> Fixes: 18fc4ebdc705 ("usb: misc: usbtest: Remove timeval usage")
> Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
>
> diff --git a/drivers/usb/misc/usbtest.c b/drivers/usb/misc/usbtest.c
> index eee82ca55b7b..113e38bfe0ef 100644
> --- a/drivers/usb/misc/usbtest.c
> +++ b/drivers/usb/misc/usbtest.c
> @@ -1964,6 +1964,9 @@ test_queue(struct usbtest_dev *dev, struct usbtest_param_32 *param,
> int status = 0;
> struct urb *urbs[param->sglen];
>
> + if (!param->sglen || param->iterations > UINT_MAX / param->sglen)
Would adding a comment here that we are checking for overflow of
context.count make sense?
It takes some time to figure out that context.count is unsigned and
hence the check is against UINT_MAX here.
> + return -EINVAL;
> +
> memset(&context, 0, sizeof(context));
> context.count = param->iterations * param->sglen;
> context.dev = dev;
> @@ -2087,6 +2090,8 @@ usbtest_do_ioctl(struct usb_interface *intf, struct usbtest_param_32 *param)
>
> if (param->iterations <= 0)
> return -EINVAL;
> + if (param->sglen > MAX_SGLEN)
> + return -EINVAL;
Right. I seem to have missed this. Thanks.
Acked-by: Deepa Dinamani <deepa.kernel@xxxxxxxxx>
-Deepa
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