Merge pull request #20927 from Firobe/dht-fix

drivers/dht: fix null deref with saul

drivers/dht/dht.c

@@ -272,8 +272,12 @@ int dht_read(dht_t *dev, int16_t *temp, int16_t *hum)
         return ret;
     }
 
-    *hum = dev->last_val.humidity;
-    *temp = dev->last_val.temperature;
+    if (hum != NULL) {
+        *hum = dev->last_val.humidity;
+    }
+    if (temp != NULL) {
+        *temp = dev->last_val.temperature;
+    }
 
     return 0;
 }

drivers/include/dht.h

@@ -107,14 +107,16 @@ typedef struct {
 int dht_init(dht_t *dev, const dht_params_t *params);
 
 /**
- * @brief   get a new temperature and humidity value from the device
+ * @brief   get a new temperature and/or humidity value from the device
  *
  * @note    if reading fails or checksum is invalid, no new values will be
  *          written into the result values
  *
  * @param[in]  dev      device descriptor of a DHT device
- * @param[out] temp     temperature value [in °C * 10^-1]
- * @param[out] hum      relative humidity value [in percent * 10^-1]
+ * @param[out] temp     temperature value [in °C * 10^-1],
+ *                      may be NULL if not needed
+ * @param[out] hum      relative humidity value [in percent * 10^-1],
+ *                      may be NULL if not needed
  *
  * @retval 0            Success
  * @retval -ENODEV      The sensor did not respond to the transmission of a

tests/drivers/dht/main.c

@@ -52,7 +52,15 @@ int main(void)
         ztimer_sleep(ZTIMER_USEC, DELAY);
 
         if (dht_read(&dev, &temp, &hum) != DHT_OK) {
-            puts("Error reading values");
+            puts("Error reading both values");
+            continue;
+        }
+        if (dht_read(&dev, &temp, NULL) != DHT_OK) {
+            puts("Error reading just temperature");
+            continue;
+        }
+        if (dht_read(&dev, NULL, &hum) != DHT_OK) {
+            puts("Error reading just humidity");
             continue;
         }