[PATCH master 2/3] common: machine_id: guard against digest algo being unavailable

[Sascha Hauer]

On Mon, Aug 08, 2022 at 08:20:09AM +0200, Ahmad Fatoum wrote:
> All callsites of digest_alloc(_by_algo) check for NULL pointer before
> proceeding except for machine_id_set_globalvar(). Fix this to fail
> more gracefully instead of the crash I ran into.
> 
> Signed-off-by: Ahmad Fatoum <a.fatoum at pengutronix.de>
> ---
>  common/machine_id.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/common/machine_id.c b/common/machine_id.c
> index a530fdeb1da8..189e74bd6796 100644
> --- a/common/machine_id.c
> +++ b/common/machine_id.c
> @@ -30,14 +30,15 @@ static int machine_id_set_globalvar(void)
>  	unsigned char machine_id[SHA1_DIGEST_SIZE];
>  	char hex_machine_id[MACHINE_ID_LENGTH];
>  	char *env_machine_id;
> -	int ret;
> +	int ret = -EOPNOTSUPP;
>  
>  	/* nothing to do if no hashable information provided */
>  	if (!__machine_id_hashable)
>  		return 0;
>  
>  	digest = digest_alloc_by_algo(HASH_ALGO_SHA1);

Had to read this twice to be sure it's correct. A plain

	if (!digest) {
		ret = -EOPNOTSUPP;
		goto out;
	}

seems easier to follow.

Sascha

> -	ret = digest_init(digest);
> +	if (digest)
> +		ret = digest_init(digest);
>  	if (ret)
>  		goto out;
>  
> -- 
> 2.30.2
> 
> 
> 

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