block/bio: Do not zero user pages

commit f55adad601c6a97c8c9628195453e0fb23b4a0ae upstream.

We don't need to zero fill the bio if not using kernel allocated pages.

Fixes: f3587d76da05 ("block: Clear kernel memory before copying to user") # v4.20-rc2
Reported-by: Todd Aiken <taiken@mvtech.ca>
Cc: Laurence Oberman <loberman@redhat.com>
Cc: stable@vger.kernel.org
Cc: Bart Van Assche <bvanassche@acm.org>
Tested-by: Laurence Oberman <loberman@redhat.com>
Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/block/bio.c b/block/bio.c
index c4ef8aa..55a5386 100644 (file)
--- a/block/bio.c
+++ b/block/bio.c
@@ -1262,7 +1262,8 @@ struct bio *bio_copy_user_iov(struct request_queue *q,
                if (ret)
                        goto cleanup;
        } else {
-               zero_fill_bio(bio);
+               if (bmd->is_our_pages)
+                       zero_fill_bio(bio);
                iov_iter_advance(iter, bio->bi_iter.bi_size);
        }