media: pvrusb2: Use kmemdup_array instead of kmemdup for multiple allocation

Let the kmemdup_array() take care about multiplication
and possible overflows.

Using kmemdup_array() is more appropriate and makes the code
easier to audit.

Signed-off-by: Shen Lichuan <[e-mail]>
Signed-off-by: Hans Verkuil <[e-mail]>

drivers/media/usb/pvrusb2/pvrusb2-io.c

···
 		if (scnt < sp->buffer_slot_count) {
 			struct pvr2_buffer **nb = NULL;
 			if (scnt) {
-				nb = kmemdup(sp->buffers, scnt * sizeof(*nb),
-					     GFP_KERNEL);
+				nb = kmemdup_array(sp->buffers, scnt, sizeof(*nb),
+						   GFP_KERNEL);
 				if (!nb) return -ENOMEM;
 			}
 			kfree(sp->buffers);