[PATCH] fastboot: mmc: Fix dest size in strlcat()

[Sean Anderson]

On 9/30/21 9:47 AM, Ariel D'Alessandro wrote:
> strlcat() is truncating the destination string to the size of the source
> string. Fix size argument in strlcat() to match the size of destination
> buffer.
>
> Bug was introduced in the following commit:
>
> commit 69a752983171c2983fc1f29c7cfa1844f41e5d8b
> Author: Sean Anderson <seanga2 at gmail.com>
>
>      fastboot: Fix possible buffer overrun
>
> Signed-off-by: Ariel D'Alessandro <ariel.dalessandro at collabora.com>
> ---
>   drivers/fastboot/fb_mmc.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/fastboot/fb_mmc.c b/drivers/fastboot/fb_mmc.c
> index cbb3f7b1dea..4c54f0c3893 100644
> --- a/drivers/fastboot/fb_mmc.c
> +++ b/drivers/fastboot/fb_mmc.c
> @@ -40,7 +40,7 @@ static int raw_part_get_info_by_name(struct blk_desc *dev_desc,
>
>   	/* check for raw partition descriptor */
>   	strcpy(env_desc_name, "fastboot_raw_partition_");
> -	strlcat(env_desc_name, name, PART_NAME_LEN);
> +	strlcat(env_desc_name, name, ARRAY_SIZE(env_desc_name));
>   	raw_part_desc = strdup(env_get(env_desc_name));
>   	if (raw_part_desc == NULL)
>   		return -ENODEV;
> @@ -114,7 +114,7 @@ static int part_get_info_by_name_or_alias(struct blk_desc **dev_desc,
>
>   		/* check for alias */
>   		strcpy(env_alias_name, "fastboot_partition_alias_");
> -		strlcat(env_alias_name, name, PART_NAME_LEN);
> +		strlcat(env_alias_name, name, ARRAY_SIZE(env_alias_name));
>   		aliased_part_name = env_get(env_alias_name);
>   		if (aliased_part_name != NULL)
>   			ret = do_get_part_info(dev_desc, aliased_part_name,
>

This looks like a duplicate of [1]. I think the only difference is
ARRAY_SIZE vs sizeof, but they are equivalent since sizeof(char) == 1.

--Sean

[1] http://patchwork.ozlabs.org/project/uboot/patch/20210730122354.6281-1-matthias.schiffer@ew.tq-group.com/