block: Clear kernel memory before copying to user

If the kernel allocates a bounce buffer for user read data, this memory
needs to be cleared before copying it to the user, otherwise it may leak
kernel memory to user space.

Laurence Oberman <loberman@redhat.com>
Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/bio.c b/block/bio.c
index 4a5a036268fb8e2dd78be6aba55a255dffb98c52..9a9c59067521304aff88b450fb8f2499bf2e7201 100644 (file)
--- a/block/bio.c
+++ b/block/bio.c
@@ -1260,6 +1260,7 @@ struct bio *bio_copy_user_iov(struct request_queue *q,
                if (ret)
                        goto cleanup;
        } else {
+               zero_fill_bio(bio);
                iov_iter_advance(iter, bio->bi_iter.bi_size);
        }