Re: [PATCH][next] platform/surface: fix potential integer overflow on shift of a int

[Maximilian Luz]

On 1/11/21 3:46 PM, Colin King wrote:
> From: Colin Ian King <colin.king@xxxxxxxxxxxxx>
>
> The left shift of int 32 bit integer constant 1 is evaluated using 32 bit
> arithmetic and then passed as a 64 bit function argument. In the case where
> func is 32 or more this can lead to an oveflow.  Avoid this by shifting
> using the BIT_ULL macro instead.
>
> Addresses-Coverity: ("Unintentional integer overflow")
> Fixes: fc00bc8ac1da ("platform/surface: Add Surface ACPI Notify driver")
> Signed-off-by: Colin Ian King <colin.king@xxxxxxxxxxxxx>
> ---
>   drivers/platform/surface/surface_acpi_notify.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/platform/surface/surface_acpi_notify.c b/drivers/platform/surface/surface_acpi_notify.c
> index 8cd67a669c86..ef9c1f8e8336 100644
> --- a/drivers/platform/surface/surface_acpi_notify.c
> +++ b/drivers/platform/surface/surface_acpi_notify.c
> @@ -188,7 +188,7 @@ static int san_acpi_notify_event(struct device *dev, u64 func,
>   	union acpi_object *obj;
>   	int status = 0;
>   
> -	if (!acpi_check_dsm(san, &SAN_DSM_UUID, SAN_DSM_REVISION, 1 << func))
> +	if (!acpi_check_dsm(san, &SAN_DSM_UUID, SAN_DSM_REVISION, BIT_ULL(func)))
>   		return 0;
>   
>   	dev_dbg(dev, "notify event %#04llx\n", func);

Thanks, looks good to me.

Reviewed-by: Maximilian Luz <luzmaximilian@xxxxxxxxx>

Regards,
Max