linux-kernel - Re: [PATCH 2/2] thermal/drivers/mediatek/lvts_thermal: Fix wrong lvts

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Date: Fri, 3 May 2024 11:45:48 -0400 (EDT)
From: Nicolas Pitre <npitre@...libre.com>
To: Julien Panis <jpanis@...libre.com>
cc: "Rafael J. Wysocki" <rafael@...nel.org>, 
    Daniel Lezcano <daniel.lezcano@...aro.org>, 
    Zhang Rui <rui.zhang@...el.com>, Lukasz Luba <lukasz.luba@....com>, 
    Matthias Brugger <matthias.bgg@...il.com>, 
    AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>, 
    linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org, 
    linux-arm-kernel@...ts.infradead.org, linux-mediatek@...ts.infradead.org
Subject: Re: [PATCH 2/2] thermal/drivers/mediatek/lvts_thermal: Fix wrong
 lvts_ctrl index

On Fri, 3 May 2024, Julien Panis wrote:

> In 'lvts_should_update_thresh()' and 'lvts_ctrl_start()' functions,
> the parameter passed to 'lvts_for_each_valid_sensor()' macro is always
> 'lvts_ctrl->lvts_data->lvts_ctrl'. In other words, the array index 0
> is systematically passed as 'struct lvts_ctrl_data' type item, even
> when another item should be consumed instead.
> 
> Hence, the 'valid_sensor_mask' value which is selected can be wrong
> because unrelated to the 'struct lvts_ctrl_data' type item that should
> be used. Hence, some thermal zone can be registered for a sensor 'i'
> that does not actually exist. Because of the invalid address used
> as 'lvts_sensor[i].msr', this situation ends up with a crash in
> 'lvts_get_temp()' function, where this 'msr' pointer is passed to
> 'readl_poll_timeout()' function. The following message is output:
> "Unable to handle kernel NULL pointer dereference at virtual
> address <msr>", with <msr> = 0.
> 
> This patch fixes the issue.
> 
> Fixes: 11e6f4c31447 ("thermal/drivers/mediatek/lvts_thermal: Allow early empty sensor slots")
> Signed-off-by: Julien Panis <jpanis@...libre.com>

Reviewed-by: Nicolas Pitre <npitre@...libre.com>

> ---
>  drivers/thermal/mediatek/lvts_thermal.c | 11 +++++++----
>  1 file changed, 7 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/thermal/mediatek/lvts_thermal.c b/drivers/thermal/mediatek/lvts_thermal.c
> index 18a796386cd0..d7df6f09938b 100644
> --- a/drivers/thermal/mediatek/lvts_thermal.c
> +++ b/drivers/thermal/mediatek/lvts_thermal.c
> @@ -116,9 +116,9 @@ struct lvts_ctrl_data {
>  			      ((s2) ? BIT(2) : 0) | \
>  			      ((s3) ? BIT(3) : 0))
>  
> -#define lvts_for_each_valid_sensor(i, lvts_ctrl_data) \
> +#define lvts_for_each_valid_sensor(i, lvts_ctrl) \
>  	for ((i) = 0; (i) < LVTS_SENSOR_MAX; (i)++) \
> -		if (!((lvts_ctrl_data)->valid_sensor_mask & BIT(i))) \
> +		if (!((lvts_ctrl)->valid_sensor_mask & BIT(i))) \
>  			continue; \
>  		else
>  
> @@ -145,6 +145,7 @@ struct lvts_ctrl {
>  	const struct lvts_data *lvts_data;
>  	u32 calibration[LVTS_SENSOR_MAX];
>  	u32 hw_tshut_raw_temp;
> +	u8 valid_sensor_mask;
>  	int mode;
>  	void __iomem *base;
>  	int low_thresh;
> @@ -356,7 +357,7 @@ static bool lvts_should_update_thresh(struct lvts_ctrl *lvts_ctrl, int high)
>  	if (high > lvts_ctrl->high_thresh)
>  		return true;
>  
> -	lvts_for_each_valid_sensor(i, lvts_ctrl->lvts_data->lvts_ctrl)
> +	lvts_for_each_valid_sensor(i, lvts_ctrl)
>  		if (lvts_ctrl->sensors[i].high_thresh == lvts_ctrl->high_thresh
>  		    && lvts_ctrl->sensors[i].low_thresh == lvts_ctrl->low_thresh)
>  			return false;
> @@ -617,6 +618,8 @@ static int lvts_sensor_init(struct device *dev, struct lvts_ctrl *lvts_ctrl,
>  		lvts_sensor[i].high_thresh = INT_MIN;
>  	};
>  
> +	lvts_ctrl->valid_sensor_mask = lvts_ctrl_data->valid_sensor_mask;
> +
>  	return 0;
>  }
>  
> @@ -1112,7 +1115,7 @@ static int lvts_ctrl_start(struct device *dev, struct lvts_ctrl *lvts_ctrl)
>  	u32 *sensor_bitmap = lvts_ctrl->mode == LVTS_MSR_IMMEDIATE_MODE ?
>  			     sensor_imm_bitmap : sensor_filt_bitmap;
>  
> -	lvts_for_each_valid_sensor(i, lvts_ctrl->lvts_data->lvts_ctrl) {
> +	lvts_for_each_valid_sensor(i, lvts_ctrl) {
>  
>  		int dt_id = lvts_sensors[i].dt_id;
>  
> 
> -- 
> 2.37.3
> 
>