Re: [PATCH 07/14] drm/i915: Validate BDB section before reading

["Kumar, Shobhit" <shobhit.kumar@intel.com>]

On 4/19/2014 2:34 AM, Rodrigo Vivi wrote:
> From: Chris Wilson <chris@chris-wilson.co.uk>
>
> Make sure that the whole BDB section is within the MMIO region prior to
> accessing it contents. That we don't read outside of the secion is left
> up to the individual section parsers.
>
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Signed-off-by: Rodrigo Vivi <rodrigo.vivi@gmail.com>
> ---
>   drivers/gpu/drm/i915/intel_bios.c | 8 +++++++-
>   1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_bios.c b/drivers/gpu/drm/i915/intel_bios.c
> index fc9e806..2945f57 100644
> --- a/drivers/gpu/drm/i915/intel_bios.c
> +++ b/drivers/gpu/drm/i915/intel_bios.c
> @@ -49,13 +49,19 @@ find_section(struct bdb_header *bdb, int section_id)
>   	total = bdb->bdb_size;
>
>   	/* walk the sections looking for section_id */
> -	while (index < total) {
> +	while (index + 3 < total) {
>   		current_id = *(base + index);
>   		index++;
> +
>   		current_size = *((u16 *)(base + index));
>   		index += 2;
> +
> +		if (index + current_size > total)
> +			return NULL;
> +
>   		if (current_id == section_id)
>   			return base + index;
> +
>   		index += current_size;
>   	}
>

Reviewed-by: Shobhit Kumar <shobhit.kumar@intel.com>