staging: most: fix mbo leak

This patch fixes a potential MBO leak in case function aim_read()
exits right after the MBO has been fetched from kfifo and before
it has been saved to the variable stacked_mbo.
Signed-off-by: Christian Gromm <christian.gromm@microchip.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/most/aim-cdev/cdev.c

@@ -237,6 +237,7 @@ aim_read(struct file *filp, char __user *buf, size_t count, loff_t *offset)
 					      (!channel->dev))))
 			return -ERESTARTSYS;
 	}
+	channel->stacked_mbo = mbo;
 
 start_copy:
 	/* make sure we don't submit to gone devices */
@@ -258,7 +259,6 @@ aim_read(struct file *filp, char __user *buf, size_t count, loff_t *offset)
 
 	if (count < mbo->processed_length) {
 		channel->mbo_offs = copied;
-		channel->stacked_mbo = mbo;
 	} else {
 		most_put_mbo(mbo);
 		channel->mbo_offs = 0;