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: eed74b3 ("crypto: rng - Fix a refcounting bug in crypto_rng_reset()") Cc: [email protected] Signed-off-by: Eric Biggers <[email protected]> Signed-off-by: Herbert Xu <[email protected]>
niw · Apr 2, 2021 · 30d0f6a · 30d0f6a
1 parent 10cb823
commit 30d0f6a
Showing 1 changed file with 3 additions and 7 deletions.
diff --git 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: