From c2176f0098d994050c88d34d37c551d033f2f18f Mon Sep 17 00:00:00 2001
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
Date: Sun, 16 Jul 2017 19:22:06 +0200
Subject: [PATCH] crypto: rng - ensure that the RNG is ready before using

Otherwise, we might be seeding the RNG using bad randomness, which is
dangerous. The one use of this function from within the kernel -- not
from userspace -- is being removed (keys/big_key), so that call site
isn't relevant in assessing this.

Cc: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
---
 crypto/rng.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/crypto/rng.c b/crypto/rng.c
index 5e8469244960f..b4a618668161d 100644
--- a/crypto/rng.c
+++ b/crypto/rng.c
@@ -43,12 +43,14 @@ int crypto_rng_reset(struct crypto_rng *tfm, const u8 *seed, unsigned int slen)
 		if (!buf)
 			return -ENOMEM;
 
-		get_random_bytes(buf, slen);
+		err = get_random_bytes_wait(buf, slen);
+		if (err)
+			goto out;
 		seed = buf;
 	}
 
 	err = crypto_rng_alg(tfm)->seed(tfm, seed, slen);
-
+out:
 	kzfree(buf);
 	return err;
 }
-- 
GitLab