media: airspy: respect the DMA coherency rules

If we want to avoid memory corruption
on incoherent architectures, buffers for DMA
must not reside
- on the stack
- embedded within other structures

Allocate them separately.

v2: fix uninitialized return value
Signed-off-by: Oliver Neukum <oneukum@suse.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

drivers/media/usb/airspy/airspy.c

@@ -123,7 +123,7 @@ struct airspy {
 
 	/* USB control message buffer */
 	#define BUF_SIZE 128
-	u8 buf[BUF_SIZE];
+	u8 *buf;
 
 	/* Current configuration */
 	unsigned int f_adc;
@@ -856,6 +856,7 @@ static void airspy_video_release(struct v4l2_device *v)
 
 	v4l2_ctrl_handler_free(&s->hdl);
 	v4l2_device_unregister(&s->v4l2_dev);
+	kfree(s->buf);
 	kfree(s);
 }
 
@@ -963,7 +964,10 @@ static int airspy_probe(struct usb_interface *intf,
 {
 	struct airspy *s;
 	int ret;
-	u8 u8tmp, buf[BUF_SIZE];
+	u8 u8tmp, *buf;
+
+	buf = NULL;
+	ret = -ENOMEM;
 
 	s = kzalloc(sizeof(struct airspy), GFP_KERNEL);
 	if (s == NULL) {
@@ -971,6 +975,13 @@ static int airspy_probe(struct usb_interface *intf,
 		return -ENOMEM;
 	}
 
+	s->buf = kzalloc(BUF_SIZE, GFP_KERNEL);
+	if (!s->buf)
+		goto err_free_mem;
+	buf = kzalloc(BUF_SIZE, GFP_KERNEL);
+	if (!buf)
+		goto err_free_mem;
+
 	mutex_init(&s->v4l2_lock);
 	mutex_init(&s->vb_queue_lock);
 	spin_lock_init(&s->queued_bufs_lock);
@@ -1068,6 +1079,8 @@ static int airspy_probe(struct usb_interface *intf,
 	v4l2_ctrl_handler_free(&s->hdl);
 	v4l2_device_unregister(&s->v4l2_dev);
 err_free_mem:
+	kfree(buf);
+	kfree(s->buf);
 	kfree(s);
 	return ret;
 }