staging: greybus: light: fix a couple double frees

The problem is in gb_lights_request_handler(). If we get a request to change the config then we release the light with gb_lights_light_release() and re-allocated it. However, if the allocation fails part way through then we call gb_lights_light_release() again. This can lead to a couple different double frees where we haven't cleared out the original values:

	gb_lights_light_v4l2_unregister(light);
	...
	kfree(light->channels);
	kfree(light->name);

I also made a small change to how we set "light->channels_count = 0;". The original code handled this part fine and did not cause a use after free but it was sort of complicated to read.

Fixes 2870b52bae4c ("greybus: lights: add lights implementation")

Signed-off-by Dan Carpenter <[email protected]>

---
 drivers/staging/greybus/light.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

drivers/staging/greybus/light.c +6 -6

index 010ae1e9c7fb..40680eaf3974 100644
@@ -1098,21 +1098,21 @@ static void gb_lights_channel_release(struct gb_channel *channel)
 static void gb_lights_light_release(struct gb_light *light)
 {
 	int i;
-	int count;
 
 	light->ready = false;
 
-	count = light->channels_count;
-
 	if (light->has_flash)
 		gb_lights_light_v4l2_unregister(light);
+	light->has_flash = false;
 
-	for (i = 0; i < count; i++) {
+	for (i = 0; i < light->channels_count; i++)
 		gb_lights_channel_release(&light->channels[i]);
-		light->channels_count--;
-	}
+	light->channels_count = 0;
+
 	kfree(light->channels);
+	light->channels = NULL;
 	kfree(light->name);
+	light->name = NULL;
 }
 
 static void gb_lights_release(struct gb_lights *glights)