Re: [PATCH] thermal/int340x_thermal: Prevent page fault on .set_mode() op

[Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>]

On Wed, 2020-07-08 at 15:46 +0200, Bartosz Szczepanek wrote:
> Starting from commit "thermal/int340x_thermal: Don't require IDSP to
> exist", priv->current_uuid_index is initialized to -1. This value may
> be passed to int3400_thermal_run_osc() from int3400_thermal_set_mode,
> contributing to page fault when accessing int3400_thermal_uuids array
> at index -1.
> 
> This commit adds a check on uuid value to int3400_thermal_run_osc.
> 
> Signed-off-by: Bartosz Szczepanek <bsz@semihalf.com>
Reviewed-by: Pandruvada, Srinivas <srinivas.pandruvada@linux.intel.com>

> ---
>  drivers/thermal/intel/int340x_thermal/int3400_thermal.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/thermal/intel/int340x_thermal/int3400_thermal.c
> b/drivers/thermal/intel/int340x_thermal/int3400_thermal.c
> index 0b3a62655843..12448ccd27f1 100644
> --- a/drivers/thermal/intel/int340x_thermal/int3400_thermal.c
> +++ b/drivers/thermal/intel/int340x_thermal/int3400_thermal.c
> @@ -216,11 +216,16 @@ static int int3400_thermal_run_osc(acpi_handle
> handle,
>  	acpi_status status;
>  	int result = 0;
>  	struct acpi_osc_context context = {
> -		.uuid_str = int3400_thermal_uuids[uuid],
> +		.uuid_str = NULL,
>  		.rev = 1,
>  		.cap.length = 8,
>  	};
>  
> +	if (uuid < 0 || uuid >= INT3400_THERMAL_MAXIMUM_UUID)
> +		return -EINVAL;
> +
> +	context.uuid_str = int3400_thermal_uuids[uuid];
> +
>  	buf[OSC_QUERY_DWORD] = 0;
>  	buf[OSC_SUPPORT_DWORD] = enable;
>