crypto: rng - Zero seed in crypto_rng_reset

If we allocate a seed on behalf ot the user in crypto_rng_reset,
we must ensure that it is zeroed afterwards or the RNG may be
compromised.
Reported-by: Stephan Mueller <smueller@chronox.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

crypto/rng.c

@@ -53,7 +53,7 @@ int crypto_rng_reset(struct crypto_rng *tfm, const u8 *seed, unsigned int slen)
 
 	err = crypto_rng_alg(tfm)->seed(tfm, seed, slen);
 
-	kfree(buf);
+	kzfree(buf);
 	return err;
 }
 EXPORT_SYMBOL_GPL(crypto_rng_reset);