From 30d0f6a956fc74bb2e948398daf3278c6b08c7e9 Mon Sep 17 00:00:00 2001
From: Eric Biggers <ebiggers@google.com>
Date: Sun, 21 Mar 2021 22:07:48 -0700
Subject: [PATCH] crypto: rng - fix crypto_rng_reset() refcounting when !CRYPTO_STATS
Git-commit: 30d0f6a956fc74bb2e948398daf3278c6b08c7e9
Patch-mainline: v5.13-rc1
References: git-fixes

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: eed74b3eba9e ("crypto: rng - Fix a refcounting bug in crypto_rng_reset()")
Cc: stable@vger.kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 crypto/rng.c | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/crypto/rng.c b/crypto/rng.c
index a888d84b524a..fea082b25fe4 100644
--- a/crypto/rng.c
+++ b/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:
-- 
2.26.2