block: check for proper length of iov entries earlier in blk_rq_map_user_iov()

commit 5478755616ae2ef1ce144dded589b62b2a50d575 upstream.

commit 9284bcf checks for proper length of iov entries in
blk_rq_map_user_iov(). But if the map is unaligned, kernel
will break out the loop without checking for the proper length.
So we need to check the proper length before the unalign check.

Signed-off-by: Xiaotian Feng <dfeng@redhat.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

diff --git a/block/blk-map.c b/block/blk-map.c
index 30a7e51589305d9504b6689c5f2587d5234ce03f..749effa7149c903b88f3f1d80d8468d7ca922b22 100644 (file)
--- a/block/blk-map.c
+++ b/block/blk-map.c
@@ -201,12 +201,13 @@ int blk_rq_map_user_iov(struct request_queue *q, struct request *rq,
        for (i = 0; i < iov_count; i++) {
                unsigned long uaddr = (unsigned long)iov[i].iov_base;
 
+               if (!iov[i].iov_len)
+                       return -EINVAL;
+
                if (uaddr & queue_dma_alignment(q)) {
                        unaligned = 1;
                        break;
                }
-               if (!iov[i].iov_len)
-                       return -EINVAL;
        }
 
        if (unaligned || (q->dma_pad_mask & len) || map_data)