bounce: don't rely on a zeroed bio_vec list

__blk_queue_bounce() relies on a zeroed bio_vec list, since it looks
up arbitrary indexes in the allocated bio. The block layer only
guarentees that added entries are valid, so clear memory after alloc.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

1 files changed, 7 insertions, 2 deletions

diff --git a/mm/bounce.c b/mm/bounce.c
index bf0cf7c8387b..e590272fe7a8 100644
--- a/mm/bounce.c
+++ b/mm/bounce.c
@@ -198,8 +198,13 @@ static void __blk_queue_bounce(struct request_queue *q, struct bio **bio_orig,
                 /*
                  * irk, bounce it
                  */
-                if (!bio)
-                        bio = bio_alloc(GFP_NOIO, (*bio_orig)->bi_vcnt);
+                if (!bio) {
+                        unsigned int cnt = (*bio_orig)->bi_vcnt;
+
+                        bio = bio_alloc(GFP_NOIO, cnt);
+                        memset(bio->bi_io_vec, 0, cnt * sizeof(struct bio_vec));
+                }
+                        
 
                 to = bio->bi_io_vec + i;