libata: ensure NCQ error result taskfile is fully initialized

before returning it via qc->result_tf.

Cc: stable@kernel.org
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

drivers/ata/libata-eh.c

@@ -1628,6 +1628,7 @@ void ata_eh_analyze_ncq_error(struct ata_link *link)
 	}
 
 	/* okay, this error is ours */
+	memset(&tf, 0, sizeof(tf));
 	rc = ata_eh_read_log_10h(dev, &tag, &tf);
 	if (rc) {
 		ata_link_printk(link, KERN_ERR, "failed to read log page 10h "