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

From: Xiaotian Feng <dfeng@redhat.com>
To: linux-kernel@vger.kernel.org
Cc: Xiaotian Feng <dfeng@redhat.com>, Jens Axboe <axboe@kernel.dk>
Subject: [PATCH] block: check for proper length of iov entries earlier in blk_rq_map_user_iov()
Date: Mon, 29 Nov 2010 17:00:55 +0800	[thread overview]
Message-ID: <1291021255-2838-1-git-send-email-dfeng@redhat.com> (raw)

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>
Cc: Jens Axboe <axboe@kernel.dk>
---
 block/blk-map.c |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/block/blk-map.c b/block/blk-map.c
index 5d5dbe4..e663ac2 100644
--- 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)
-- 
1.7.3.2

