crypto: rng - fix crypto_rng_reset() refcounting when !CRYPTO_STATS

crypto_stats_get() is a no-op when the kernel is compiled without
CONFIG_CRYPTO_STATS, so pairing it with crypto_alg_put() unconditionally
(as crypto_rng_reset() does) is wrong.

Fix this by moving the call to crypto_stats_get() to just before the
actual algorithm operation which might need it.  This makes it always
paired with crypto_stats_rng_seed().

Fixes: eed74b3e ("crypto: rng - Fix a refcounting bug in crypto_rng_reset()")
Cc: stable@vger.kernel.org
Signed-off-by: NEric Biggers <ebiggers@google.com>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

crypto/rng.c

@@ -34,22 +34,18 @@ int crypto_rng_reset(struct crypto_rng *tfm, const u8 *seed, unsigned int slen)
 	u8 *buf = NULL;
 	int err;
 
-	crypto_stats_get(alg);
 	if (!seed && slen) {
 		buf = kmalloc(slen, GFP_KERNEL);
-		if (!buf) {
-			crypto_alg_put(alg);
+		if (!buf)
 			return -ENOMEM;
-		}
 
 		err = get_random_bytes_wait(buf, slen);
-		if (err) {
-			crypto_alg_put(alg);
+		if (err)
 			goto out;
-		}
 		seed = buf;
 	}
 
+	crypto_stats_get(alg);
 	err = crypto_rng_alg(tfm)->seed(tfm, seed, slen);
 	crypto_stats_rng_seed(alg, err);
 out: