crypto: rng - Fix a refcounting bug in crypto_rng_reset()

commit eed74b3e upstream.

We need to decrement this refcounter on these error paths.

Fixes: f7d76e05

 ("crypto: user - fix use_after_free of struct xxx_request")
Cc: <stable@vger.kernel.org>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

crypto/rng.c

@@ -37,12 +37,16 @@ int crypto_rng_reset(struct crypto_rng *tfm, const u8 *seed, unsigned int slen)
 	crypto_stats_get(alg);
 	if (!seed && slen) {
 		buf = kmalloc(slen, GFP_KERNEL);
-		if (!buf)
+		if (!buf) {
+			crypto_alg_put(alg);
 			return -ENOMEM;
+		}
 
 		err = get_random_bytes_wait(buf, slen);
-		if (err)
+		if (err) {
+			crypto_alg_put(alg);
 			goto out;
+		}
 		seed = buf;
 	}