Re: [PATCH v5.15-v5.10] drm/amd/pm: Fix the null pointer dereference for vega10_hwmgr

[Alex Deucher]

On Tue, Sep 3, 2024 at 5:53 AM sikkamukul <mukul.sikka@xxxxxxxxxxxx> wrote:
>
> From: Bob Zhou <bob.zhou@xxxxxxx>
>
> [ Upstream commit 50151b7f1c79a09117837eb95b76c2de76841dab ]
>
> Check return value and conduct null pointer handling to avoid null pointer dereference.
>
> Signed-off-by: Bob Zhou <bob.zhou@xxxxxxx>
> Reviewed-by: Tim Huang <Tim.Huang@xxxxxxx>
> Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
> Signed-off-by: Mukul Sikka <mukul.sikka@xxxxxxxxxxxx>

Just out of curiosity, are you actually seeing an issue?  This and a
lot of the other recent NULL check patches are just static checker
fixes.  They don't actually fix a known issue.

Alex

> ---
>  .../drm/amd/pm/powerplay/hwmgr/vega10_hwmgr.c | 30 ++++++++++++++++---
>  1 file changed, 26 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/pm/powerplay/hwmgr/vega10_hwmgr.c b/drivers/gpu/drm/amd/pm/powerplay/hwmgr/vega10_hwmgr.c
> index 10678b519..304874cba 100644
> --- a/drivers/gpu/drm/amd/pm/powerplay/hwmgr/vega10_hwmgr.c
> +++ b/drivers/gpu/drm/amd/pm/powerplay/hwmgr/vega10_hwmgr.c
> @@ -3391,13 +3391,17 @@ static int vega10_find_dpm_states_clocks_in_dpm_table(struct pp_hwmgr *hwmgr, co
>         const struct vega10_power_state *vega10_ps =
>                         cast_const_phw_vega10_power_state(states->pnew_state);
>         struct vega10_single_dpm_table *sclk_table = &(data->dpm_table.gfx_table);
> -       uint32_t sclk = vega10_ps->performance_levels
> -                       [vega10_ps->performance_level_count - 1].gfx_clock;
>         struct vega10_single_dpm_table *mclk_table = &(data->dpm_table.mem_table);
> -       uint32_t mclk = vega10_ps->performance_levels
> -                       [vega10_ps->performance_level_count - 1].mem_clock;
> +       uint32_t sclk, mclk;
>         uint32_t i;
>
> +       if (vega10_ps == NULL)
> +               return -EINVAL;
> +       sclk = vega10_ps->performance_levels
> +                       [vega10_ps->performance_level_count - 1].gfx_clock;
> +       mclk = vega10_ps->performance_levels
> +                       [vega10_ps->performance_level_count - 1].mem_clock;
> +
>         for (i = 0; i < sclk_table->count; i++) {
>                 if (sclk == sclk_table->dpm_levels[i].value)
>                         break;
> @@ -3704,6 +3708,9 @@ static int vega10_generate_dpm_level_enable_mask(
>                         cast_const_phw_vega10_power_state(states->pnew_state);
>         int i;
>
> +       if (vega10_ps == NULL)
> +               return -EINVAL;
> +
>         PP_ASSERT_WITH_CODE(!vega10_trim_dpm_states(hwmgr, vega10_ps),
>                         "Attempt to Trim DPM States Failed!",
>                         return -1);
> @@ -4828,6 +4835,9 @@ static int vega10_check_states_equal(struct pp_hwmgr *hwmgr,
>
>         psa = cast_const_phw_vega10_power_state(pstate1);
>         psb = cast_const_phw_vega10_power_state(pstate2);
> +       if (psa == NULL || psb == NULL)
> +               return -EINVAL;
> +
>         /* If the two states don't even have the same number of performance levels they cannot be the same state. */
>         if (psa->performance_level_count != psb->performance_level_count) {
>                 *equal = false;
> @@ -4953,6 +4963,8 @@ static int vega10_set_sclk_od(struct pp_hwmgr *hwmgr, uint32_t value)
>                 return -EINVAL;
>
>         vega10_ps = cast_phw_vega10_power_state(&ps->hardware);
> +       if (vega10_ps == NULL)
> +               return -EINVAL;
>
>         vega10_ps->performance_levels
>         [vega10_ps->performance_level_count - 1].gfx_clock =
> @@ -5004,6 +5016,8 @@ static int vega10_set_mclk_od(struct pp_hwmgr *hwmgr, uint32_t value)
>                 return -EINVAL;
>
>         vega10_ps = cast_phw_vega10_power_state(&ps->hardware);
> +       if (vega10_ps == NULL)
> +               return -EINVAL;
>
>         vega10_ps->performance_levels
>         [vega10_ps->performance_level_count - 1].mem_clock =
> @@ -5239,6 +5253,9 @@ static void vega10_odn_update_power_state(struct pp_hwmgr *hwmgr)
>                 return;
>
>         vega10_ps = cast_phw_vega10_power_state(&ps->hardware);
> +       if (vega10_ps == NULL)
> +               return;
> +
>         max_level = vega10_ps->performance_level_count - 1;
>
>         if (vega10_ps->performance_levels[max_level].gfx_clock !=
> @@ -5261,6 +5278,9 @@ static void vega10_odn_update_power_state(struct pp_hwmgr *hwmgr)
>
>         ps = (struct pp_power_state *)((unsigned long)(hwmgr->ps) + hwmgr->ps_size * (hwmgr->num_ps - 1));
>         vega10_ps = cast_phw_vega10_power_state(&ps->hardware);
> +       if (vega10_ps == NULL)
> +               return;
> +
>         max_level = vega10_ps->performance_level_count - 1;
>
>         if (vega10_ps->performance_levels[max_level].gfx_clock !=
> @@ -5451,6 +5471,8 @@ static int vega10_get_performance_level(struct pp_hwmgr *hwmgr, const struct pp_
>                 return -EINVAL;
>
>         ps = cast_const_phw_vega10_power_state(state);
> +       if (ps == NULL)
> +               return -EINVAL;
>
>         i = index > ps->performance_level_count - 1 ?
>                         ps->performance_level_count - 1 : index;
> --
> 2.39.4
>