crypto: rng - Ensure set_ent is always present

commit c0d3672 upstream.

Ensure that set_ent is always set since only drbg provides it.

Fixes: 77ebdab ("crypto: af_alg - add extra parameters for DRBG interface")
Reported-by: Yiqi Sun <sunyiqixm@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: herbertx

crypto/rng.c

@@ -167,6 +167,11 @@ int crypto_del_default_rng(void)
 EXPORT_SYMBOL_GPL(crypto_del_default_rng);
 #endif
 
+static void rng_default_set_ent(struct crypto_rng *tfm, const u8 *data,
+				unsigned int len)
+{
+}
+
 int crypto_register_rng(struct rng_alg *alg)
 {
 	struct crypto_alg *base = &alg->base;
@@ -178,6 +183,9 @@ int crypto_register_rng(struct rng_alg *alg)
 	base->cra_flags &= ~CRYPTO_ALG_TYPE_MASK;
 	base->cra_flags |= CRYPTO_ALG_TYPE_RNG;
 
+	if (!alg->set_ent)
+		alg->set_ent = rng_default_set_ent;
+
 	return crypto_register_alg(base);
 }
 EXPORT_SYMBOL_GPL(crypto_register_rng);