linux-kernel - [PATCH v5 09/13] rhashtable: use get_random_u32 for hash

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Message-Id: <20170607232607.26870-10-Jason@zx2c4.com>
Date:   Thu,  8 Jun 2017 01:26:03 +0200
From:   "Jason A. Donenfeld" <Jason@...c4.com>
To:     Theodore Ts'o <tytso@....edu>,
        Linux Crypto Mailing List <linux-crypto@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        kernel-hardening@...ts.openwall.com,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Eric Biggers <ebiggers3@...il.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        David Miller <davem@...emloft.net>
Cc:     "Jason A. Donenfeld" <Jason@...c4.com>,
        Thomas Graf <tgraf@...g.ch>,
        Herbert Xu <herbert@...dor.apana.org.au>
Subject: [PATCH v5 09/13] rhashtable: use get_random_u32 for hash_rnd

This is much faster and just as secure. It also has the added benefit of
probably returning better randomness at early-boot on systems with
architectural RNGs.

Signed-off-by: Jason A. Donenfeld <Jason@...c4.com>
Cc: Thomas Graf <tgraf@...g.ch>
Cc: Herbert Xu <herbert@...dor.apana.org.au>
---
 lib/rhashtable.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/rhashtable.c b/lib/rhashtable.c
index d9e7274a04cd..a1eb7c947f46 100644
--- a/lib/rhashtable.c
+++ b/lib/rhashtable.c
@@ -235,7 +235,7 @@ static struct bucket_table *bucket_table_alloc(struct rhashtable *ht,
 
 	INIT_LIST_HEAD(&tbl->walkers);
 
-	get_random_bytes(&tbl->hash_rnd, sizeof(tbl->hash_rnd));
+	tbl->hash_rnd = get_random_u32();
 
 	for (i = 0; i < nbuckets; i++)
 		INIT_RHT_NULLS_HEAD(tbl->buckets[i], ht, i);
-- 
2.13.0