[PATCH] drm/amd/amdgpu: default to zero number of states if not enabled

[Alex Deucher]

On Thu, Oct 6, 2016 at 2:02 PM, Colin King <colin.king at canonical.com> wrote:
> From: Colin Ian King <colin.king at canonical.com>
>
> Currently, if adev->pp_enabled is false then the pp_stats_info data
> is not read and hence a garbage number of states from the stack
> is used to dump out the number of states. Given data.nums could be
> any random value, this could easily lead to read outside the
> data.states array.  Fix this by setting data.nums to zero if
> adev->pp_enabled is false.

Are you actually seeing a problem?  The pp_num_states attribute only
gets added in the first place if pp_enabled is true.

Alex

>
> Signed-off-by: Colin Ian King <colin.king at canonical.com>
> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c
> index accc908..808d788 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c
> @@ -195,6 +195,8 @@ static ssize_t amdgpu_get_pp_num_states(struct device *dev,
>
>         if (adev->pp_enabled)
>                 amdgpu_dpm_get_pp_num_states(adev, &data);
> +       else
> +               data.nums = 0;
>
>         buf_len = snprintf(buf, PAGE_SIZE, "states: %d\n", data.nums);
>         for (i = 0; i < data.nums; i++)
> --
> 2.9.3
>
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