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

[Eric Biggers]

From: Eric Biggers <ebigg...@google.com>

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: sta...@vger.kernel.org
Signed-off-by: Eric Biggers <ebigg...@google.com>
---
 crypto/rng.c | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/crypto/rng.c b/crypto/rng.c
index a888d84b524a4..fea082b25fe4b 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:
-- 
2.31.0