[PATCH] drm/amdgpu: fix potential null dereference

[Alex Deucher]

Applied.  Thanks!

Alex

On Wed, Mar 2, 2022 at 3:56 AM Weiguo Li <liwg06 at foxmail.com> wrote:
>
> "ctx" is dereferenced but null checked later. Swap their positions
> to avoid potential null dereference.
>
> Found using a Coccinelle script:
> https://coccinelle.gitlabpages.inria.fr/website/rules/mini_null_ref.cocci
>
> Signed-off-by: Weiguo Li <liwg06 at foxmail.com>
> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c
> index f522b52725e4..b4f035ce44bc 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ctx.c
> @@ -258,11 +258,12 @@ static void amdgpu_ctx_fini_entity(struct amdgpu_ctx_entity *entity)
>  static int amdgpu_ctx_get_stable_pstate(struct amdgpu_ctx *ctx,
>                                         u32 *stable_pstate)
>  {
> -       struct amdgpu_device *adev = ctx->adev;
> +       struct amdgpu_device *adev;
>         enum amd_dpm_forced_level current_level;
>
>         if (!ctx)
>                 return -EINVAL;
> +       adev = ctx->adev;
>
>         current_level = amdgpu_dpm_get_performance_level(adev);
>
> @@ -289,12 +290,13 @@ static int amdgpu_ctx_get_stable_pstate(struct amdgpu_ctx *ctx,
>  static int amdgpu_ctx_set_stable_pstate(struct amdgpu_ctx *ctx,
>                                         u32 stable_pstate)
>  {
> -       struct amdgpu_device *adev = ctx->adev;
> +       struct amdgpu_device *adev;
>         enum amd_dpm_forced_level level;
>         int r;
>
>         if (!ctx)
>                 return -EINVAL;
> +       adev = ctx->adev;
>
>         mutex_lock(&adev->pm.stable_pstate_ctx_lock);
>         if (adev->pm.stable_pstate_ctx && adev->pm.stable_pstate_ctx != ctx) {
> --
> 2.25.1
>