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

Ensure that we pass down properly validated iov segments before
calling into the mapping or copy functions.

Reported-by: Dan Rosenberg <drosenberg@vsecurity.com>
Cc: stable@kernel.org
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/block/blk-map.c b/block/blk-map.c
index d4a586d8691e..5d5dbe47c228 100644
--- a/block/blk-map.c
+++ b/block/blk-map.c
@@ -205,6 +205,8 @@ int blk_rq_map_user_iov(struct request_queue *q, struct request *rq,
                         unaligned = 1;
                         break;
                 }
+                if (!iov[i].iov_len)
+                        return -EINVAL;
         }
 
         if (unaligned || (q->dma_pad_mask & len) || map_data)