block: Always check length of all iov entries in blk_rq_map_user_iov()

Even after commit 54787556
("block: check for proper length of iov entries earlier ...")
we still won't check for zero-length entries after an unaligned
entry.  Remove the break-statement, so all entries are checked.
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Cc: stable@vger.kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block/blk-map.c

@@ -204,10 +204,11 @@ int blk_rq_map_user_iov(struct request_queue *q, struct request *rq,
 		if (!iov[i].iov_len)
 			return -EINVAL;
 
-		if (uaddr & queue_dma_alignment(q)) {
+		/*
+		 * Keep going so we check length of all segments
+		 */
+		if (uaddr & queue_dma_alignment(q))
 			unaligned = 1;
-			break;
-		}
 	}
 
 	if (unaligned || (q->dma_pad_mask & len) || map_data)