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

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Message-Id: <20240503-mtk-thermal-lvts-ctrl-idx-fix-v1-2-f605c50ca117@baylibre.com>
Date: Fri, 03 May 2024 17:35:14 +0200
From: Julien Panis <jpanis@...libre.com>
To: "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>, 
 Nicolas Pitre <npitre@...libre.com>
Cc: linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org, 
 linux-arm-kernel@...ts.infradead.org, linux-mediatek@...ts.infradead.org, 
 Julien Panis <jpanis@...libre.com>
Subject: [PATCH 2/2] thermal/drivers/mediatek/lvts_thermal: Fix wrong
 lvts_ctrl index

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>
---
 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