drivers: sensor: scd4x: fix int overflow on val2 for temp and hum

thomzach · kartben · commit 7e23a18980c3 · 2025-02-21T04:39:42.000+01:00
The scd4x_channel_get function converts raw word values to
struct sensor_value's per the datasheet. The calculation for val2 of a
struct sensor_value `val-&gt;val2 = ((tmp_val % 0xFFFF) * 1000000) / 0xFFFF;`
can overflow the max of int32_t, resulting in an incorrect
sensor_value.
Fix it by changing the type of tmp_val to int64_t.

Signed-off-by: Zach Thomas &lt;zach.thomas1.zt@gmail.com&gt;
diff --git a/drivers/sensor/sensirion/scd4x/scd4x.c b/drivers/sensor/sensirion/scd4x/scd4x.c
@@ -630,7 +630,7 @@ static int scd4x_channel_get(const struct device *dev, enum sensor_channel chan,
 			     struct sensor_value *val)
 {
 	const struct scd4x_data *data = dev->data;
-	int32_t tmp_val;
+	int64_t tmp_val;
 
 	switch ((enum sensor_channel)chan) {
 	case SENSOR_CHAN_AMBIENT_TEMP:

Original file line number	Diff line number	Diff line change
`@@ -630,7 +630,7 @@ static int scd4x_channel_get(const struct device *dev, enum sensor_channel chan,`
`630`	`630`	`struct sensor_value *val)`
`631`	`631`	`{`
`632`	`632`	`const struct scd4x_data *data = dev->data;`
`633`		`- int32_t tmp_val;`
	`633`	`+ int64_t tmp_val;`
`634`	`634`
`635`	`635`	`switch ((enum sensor_channel)chan) {`
`636`	`636`	`case SENSOR_CHAN_AMBIENT_TEMP:`