prevent segfault caused by bitidx++

larsks · larsks · commit 7d2ef0ac3d58 · 2014-05-15T21:02:31.000-04:00
This patch modifies Adafruit_DHT_Driver/Adafruit_DHT.c so that the code that increments `bitidx` without bound is protected by #ifdef DEBUG. This prevents this code from generating a segfault if readDHT is called several times (which will ultimately cause bitidx to increment beyond the end of the bits array). Resolves github issue adafruit#78.
diff --git a/Adafruit_DHT_Driver/Adafruit_DHT.c b/Adafruit_DHT_Driver/Adafruit_DHT.c
@@ -105,7 +105,9 @@ int readDHT(int type, int pin) {
     }
     laststate = bcm2835_gpio_lev(pin);
     if (counter == 1000) break;
+#ifdef DEBUG
     bits[bitidx++] = counter;
+#endif
 
     if ((i>3) && (i%2 == 0)) {
       // shove each bit into the storage bytes

Original file line number	Diff line number	Diff line change
`@@ -105,7 +105,9 @@ int readDHT(int type, int pin) {`
`105`	`105`	`}`
`106`	`106`	`laststate = bcm2835_gpio_lev(pin);`
`107`	`107`	`if (counter == 1000) break;`
	`108`	`+#ifdef DEBUG`
`108`	`109`	`bits[bitidx++] = counter;`
	`110`	`+#endif`
`109`	`111`
`110`	`112`	`if ((i>3) && (i%2 == 0)) {`
`111`	`113`	`// shove each bit into the storage bytes`