crypto: n2 - Silence gcc format-truncation false positive warnings

The heuristics used by gcc triggers false positive truncation
warnings in hifn_alg_alloc.

Add checks on snprintf calls to silence these warnings, including
the one for cra_driver_name even though it does not currently trigger
a gcc warning.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

drivers/crypto/n2_core.c

@@ -1382,8 +1382,12 @@ static int __n2_register_one_hmac(struct n2_ahash_alg *n2ahash)
 	ahash->setkey = n2_hmac_async_setkey;
 
 	base = &ahash->halg.base;
-	snprintf(base->cra_name, CRYPTO_MAX_ALG_NAME, "hmac(%s)", p->child_alg);
-	snprintf(base->cra_driver_name, CRYPTO_MAX_ALG_NAME, "hmac-%s-n2", p->child_alg);
+	if (snprintf(base->cra_name, CRYPTO_MAX_ALG_NAME, "hmac(%s)",
+		     p->child_alg) >= CRYPTO_MAX_ALG_NAME)
+		goto out_free_p;
+	if (snprintf(base->cra_driver_name, CRYPTO_MAX_ALG_NAME, "hmac-%s-n2",
+		     p->child_alg) >= CRYPTO_MAX_ALG_NAME)
+		goto out_free_p;
 
 	base->cra_ctxsize = sizeof(struct n2_hmac_ctx);
 	base->cra_init = n2_hmac_cra_init;
@@ -1394,6 +1398,7 @@ static int __n2_register_one_hmac(struct n2_ahash_alg *n2ahash)
 	if (err) {
 		pr_err("%s alg registration failed\n", base->cra_name);
 		list_del(&p->derived.entry);
+out_free_p:
 		kfree(p);
 	} else {
 		pr_info("%s alg registered\n", base->cra_name);