[dm-devel] [PATCH] dm-verity: Fix biovecs hash calculation regression

[Mikulas Patocka]

On Mon, 14 Apr 2014, Milan Broz wrote:

> The commit
>   003b5c5719f159f4f4bf97511c4702a0638313dd
>   block: Convert drivers to immutable biovecs
> 
> incorrectly converted biovec iteration in dm-verity to always
> calculate hash from full biovec, while the function need
> to calculate hash only from part of it (up to "todo"
> calculated value).
> 
> This patch fixes the issue by limiting hash input to only
> really requested data size.
> 
> The problem is easily reproducible using cryptsetup
> regression test for veritysetup (verity-compat-test).
> 
> (Patch should be applied also to 3.14 stable.)
> 
> Signed-off-by: Milan Broz <gmazyland at gmail.com>

Acked-by: Mikulas Patocka <mpatocka at redhat.com>
Cc: stable at vger.kernel.org	# 3.14

> ---
>  drivers/md/dm-verity.c | 15 +++++++++------
>  1 file changed, 9 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/md/dm-verity.c b/drivers/md/dm-verity.c
> index 796007a..7a7bab8 100644
> --- a/drivers/md/dm-verity.c
> +++ b/drivers/md/dm-verity.c
> @@ -330,15 +330,17 @@ test_block_hash:
>  				return r;
>  			}
>  		}
> -
>  		todo = 1 << v->data_dev_block_bits;
> -		while (io->iter.bi_size) {
> +		do {
>  			u8 *page;
> +			unsigned len;
>  			struct bio_vec bv = bio_iter_iovec(bio, io->iter);
>  
>  			page = kmap_atomic(bv.bv_page);
> -			r = crypto_shash_update(desc, page + bv.bv_offset,
> -						bv.bv_len);
> +			len = bv.bv_len;
> +			if (likely(len >= todo))
> +				len = todo;
> +			r = crypto_shash_update(desc, page + bv.bv_offset, len);
>  			kunmap_atomic(page);
>  
>  			if (r < 0) {
> @@ -346,8 +348,9 @@ test_block_hash:
>  				return r;
>  			}
>  
> -			bio_advance_iter(bio, &io->iter, bv.bv_len);
> -		}
> +			bio_advance_iter(bio, &io->iter, len);
> +			todo -= len;
> +		} while (todo);
>  
>  		if (!v->version) {
>  			r = crypto_shash_update(desc, v->salt, v->salt_size);
> -- 
> 1.9.2
>