linux-kernel - Re: [PATCH] dm-verity: do forward error correction on metadata I/O errors

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CABCJKucmOTVF1jY3vM7VKHuLkDeUxK1EU7YK=C+vgfWvgZFWPQ@mail.gmail.com>
Date: Mon, 10 Feb 2025 08:57:55 -0800
From: Sami Tolvanen <samitolvanen@...gle.com>
To: Mikulas Patocka <mpatocka@...hat.com>
Cc: Akilesh Kailash <akailash@...gle.com>, kernel-team@...roid.com, 
	Alasdair Kergon <agk@...hat.com>, Mike Snitzer <snitzer@...nel.org>, Milan Broz <gmazyland@...il.com>, 
	dm-devel@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] dm-verity: do forward error correction on metadata I/O errors

Hi Mikulas,

On Mon, Feb 10, 2025 at 7:04 AM Mikulas Patocka <mpatocka@...hat.com> wrote:
>
> Do forward error correction if metadata I/O fails.
>
> Signed-off-by: Mikulas Patocka <mpatocka@...hat.com>
>
> ---
>  drivers/md/dm-verity-target.c |   19 +++++++++++++++++--
>  1 file changed, 17 insertions(+), 2 deletions(-)
>
> Index: linux-2.6/drivers/md/dm-verity-target.c
> ===================================================================
> --- linux-2.6.orig/drivers/md/dm-verity-target.c        2025-02-04 13:52:45.000000000 +0100
> +++ linux-2.6/drivers/md/dm-verity-target.c     2025-02-10 15:55:42.000000000 +0100
> @@ -324,8 +324,22 @@ static int verity_verify_level(struct dm
>                                                 &buf, bio->bi_ioprio);
>         }
>
> -       if (IS_ERR(data))
> -               return PTR_ERR(data);
> +       if (IS_ERR(data)) {
> +               r = PTR_ERR(data);
> +               data = dm_bufio_new(v->bufio, hash_block, &buf);
> +               if (IS_ERR(data))
> +                       return r;
> +               if (verity_fec_decode(v, io, DM_VERITY_BLOCK_TYPE_METADATA,
> +                                     hash_block, data) == 0) {
> +                       aux = dm_bufio_get_aux_data(buf);
> +                       aux->hash_verified = 1;
> +                       goto release_ok;
> +               } else {
> +                       dm_bufio_release(buf);
> +                       dm_bufio_forget(v->bufio, hash_block);
> +                       return r;
> +               }
> +       }

Don't we still have to check for io->in_bh before trying to correct the error?

Overall, it would be nice not to duplicate code here. Should the
metadata error correction / handling be moved to a separate function
similar to verity_handle_data_hash_mismatch?

Sami