Re: [PATCH] ima: fix reference leak in asymmetric_verify()

[Stefan Berger <stefanb@linux.ibm.com>]

On 1/13/22 14:44, Eric Biggers wrote:
> From: Eric Biggers <ebiggers@google.com>
>
> Don't leak a reference to the key if its algorithm is unknown.
>
> Fixes: 947d70597236 ("ima: Support EC keys for signature verification")
> Cc: <stable@vger.kernel.org> # v5.13+
> Signed-off-by: Eric Biggers <ebiggers@google.com>
> ---
>   security/integrity/digsig_asymmetric.c | 15 +++++++++------
>   1 file changed, 9 insertions(+), 6 deletions(-)
>
> diff --git a/security/integrity/digsig_asymmetric.c b/security/integrity/digsig_asymmetric.c
> index 23240d793b07..895f4b9ce8c6 100644
> --- a/security/integrity/digsig_asymmetric.c
> +++ b/security/integrity/digsig_asymmetric.c
> @@ -109,22 +109,25 @@ int asymmetric_verify(struct key *keyring, const char *sig,
>   
>   	pk = asymmetric_key_public_key(key);
>   	pks.pkey_algo = pk->pkey_algo;
> -	if (!strcmp(pk->pkey_algo, "rsa"))
> +	if (!strcmp(pk->pkey_algo, "rsa")) {
>   		pks.encoding = "pkcs1";
> -	else if (!strncmp(pk->pkey_algo, "ecdsa-", 6))
> +	} else if (!strncmp(pk->pkey_algo, "ecdsa-", 6)) {
>   		/* edcsa-nist-p192 etc. */
>   		pks.encoding = "x962";
> -	else if (!strcmp(pk->pkey_algo, "ecrdsa") ||
> -		   !strcmp(pk->pkey_algo, "sm2"))
> +	} else if (!strcmp(pk->pkey_algo, "ecrdsa") ||
> +		   !strcmp(pk->pkey_algo, "sm2")) {
>   		pks.encoding = "raw";
> -	else
> -		return -ENOPKG;
> +	} else {
> +		ret = -ENOPKG;
> +		goto out;
> +	}
>   
>   	pks.digest = (u8 *)data;
>   	pks.digest_size = datalen;
>   	pks.s = hdr->sig;
>   	pks.s_size = siglen;
>   	ret = verify_signature(key, &pks);
> +out:
>   	key_put(key);
>   	pr_debug("%s() = %d\n", __func__, ret);
>   	return ret;
>
> base-commit: feb7a43de5ef625ad74097d8fd3481d5dbc06a59


Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>