check ASN1 type before using it

engines/ccgost/gost_crypt.c

@@ -459,13 +459,15 @@ int  gost89_get_asn1_parameters(EVP_CIPHER_CTX *ctx,ASN1_TYPE *params)
 	int ret = -1;
 	int len; 
 	GOST_CIPHER_PARAMS *gcp = NULL;
-	unsigned char *p = params->value.sequence->data;
+	unsigned char *p;
 	struct ossl_gost_cipher_ctx *c=ctx->cipher_data;
 	if (ASN1_TYPE_get(params) != V_ASN1_SEQUENCE)
 		{
 		return ret;
 		}
 
+	p = params->value.sequence->data;
+
 	gcp = d2i_GOST_CIPHER_PARAMS(NULL, (const unsigned char **)&p,
 		params->value.sequence->length);