Re: [PATCH 17/17] luks2: Fix use of incorrect index and some error messages.

[Patrick Steinhardt]

On Wed, Jul 29, 2020 at 04:50:22PM -0500, development@efficientek.com wrote:
> From: Glenn Washburn <development@efficientek.com>
> 
> Signed-off-by: Glenn Washburn <development@efficientek.com>
> ---
>  grub-core/disk/luks2.c | 14 +++++++-------
>  1 file changed, 7 insertions(+), 7 deletions(-)
> 
> diff --git a/grub-core/disk/luks2.c b/grub-core/disk/luks2.c
> index 44a73d2b8..48600db68 100644
> --- a/grub-core/disk/luks2.c
> +++ b/grub-core/disk/luks2.c
> @@ -277,34 +277,34 @@ luks2_get_keyslot (grub_luks2_keyslot_t *k, 
> grub_luks2_digest_t *d, grub_luks2_s
>      return grub_error (GRUB_ERR_BAD_ARGUMENT, "Could not get digests");
>    for (j = 0; j < size; j++)
>      {
> -      if (grub_json_getchild (&digest, &digests, i) ||
> +      if (grub_json_getchild (&digest, &digests, j) ||
>            grub_json_getchild (&digest, &digest, 0) ||
>            luks2_parse_digest (d, &digest))
> -     return grub_error (GRUB_ERR_BAD_ARGUMENT, "Could not parse digest 
> %"PRIuGRUB_SIZE, i);
> +     return grub_error (GRUB_ERR_BAD_ARGUMENT, "Could not parse digest 
> %"PRIuGRUB_SIZE, j);
>  
>        if ((d->keyslots & (1 << idx)))
>       break;
>      }
>    if (j == size)
> -      return grub_error (GRUB_ERR_FILE_NOT_FOUND, "No digest for keyslot 
> %"PRIuGRUB_SIZE);
> +      return grub_error (GRUB_ERR_FILE_NOT_FOUND, "No digest for keyslot 
> %"PRIuGRUB_SIZE, i);

These look correct to me.

>    /* Get segment that matches the digest. */
>    if (grub_json_getvalue (&segments, root, "segments") ||
>        grub_json_getsize (&size, &segments))
>      return grub_error (GRUB_ERR_BAD_ARGUMENT, "Could not get segments");
> -  for (j = 0; j < size; j++)
> +  for (i = j, j = 0; j < size; j++)

Why do we reassign `i = j` here? I think it's to fix the "No segment for
digest" message below which previously referred to the wrong digest,
right? I think we should just stop using `i` and `j` here. If we renamed
them `keyslot_index` and `digest_index`, respectively, and only use `i`
as a loop variable, then the code would be much easier to read.

>      {
> -      if (grub_json_getchild (&segment, &segments, i) ||
> +      if (grub_json_getchild (&segment, &segments, j) ||
>         grub_json_getuint64 (&idx, &segment, NULL) ||
>         grub_json_getchild (&segment, &segment, 0) ||
>            luks2_parse_segment (s, &segment))
> -     return grub_error (GRUB_ERR_BAD_ARGUMENT, "Could not parse segment 
> %"PRIuGRUB_SIZE, i);
> +     return grub_error (GRUB_ERR_BAD_ARGUMENT, "Could not parse segment 
> %"PRIuGRUB_SIZE, j);
>  
>        if ((d->segments & (1 << idx)))
>       break;
>      }
>    if (j == size)
> -    return grub_error (GRUB_ERR_FILE_NOT_FOUND, "No segment for digest 
> %"PRIuGRUB_SIZE);
> +    return grub_error (GRUB_ERR_FILE_NOT_FOUND, "No segment for digest 
> %"PRIuGRUB_SIZE, i);
>  
>    return GRUB_ERR_NONE;
>  }
> -- 
> 2.25.1
>

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