linux-kernel - [PATCH 4/7] random: properly align get_random_int

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Message-Id: <1465832919-11316-5-git-send-email-tytso@mit.edu>
Date:	Mon, 13 Jun 2016 11:48:36 -0400
From:	Theodore Ts'o <tytso@....edu>
To:	Linux Kernel Developers List <linux-kernel@...r.kernel.org>
Cc:	linux-crypto@...r.kernel.org, smueller@...onox.de,
	herbert@...dor.apana.org.au, andi@...stfloor.org,
	sandyinchina@...il.com, jsd@...n.com, hpa@...or.com,
	Eric Biggers <ebiggers3@...il.com>, stable@...nel.org,
	Theodore Ts'o <tytso@....edu>
Subject: [PATCH 4/7] random: properly align get_random_int_hash

From: Eric Biggers <ebiggers3@...il.com>

get_random_long() reads from the get_random_int_hash array using an
unsigned long pointer.  For this code to be guaranteed correct on all
architectures, the array must be aligned to an unsigned long boundary.

Cc: stable@...nel.org
Signed-off-by: Eric Biggers <ebiggers3@...il.com>
Signed-off-by: Theodore Ts'o <tytso@....edu>
---
 drivers/char/random.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/char/random.c b/drivers/char/random.c
index 64e35a4..83f5cd0 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -1778,13 +1778,15 @@ int random_int_secret_init(void)
 	return 0;
 }
 
+static DEFINE_PER_CPU(__u32 [MD5_DIGEST_WORDS], get_random_int_hash)
+		__aligned(sizeof(unsigned long));
+
 /*
  * Get a random word for internal kernel use only. Similar to urandom but
  * with the goal of minimal entropy pool depletion. As a result, the random
  * value is not cryptographically secure but for several uses the cost of
  * depleting entropy is too high
  */
-static DEFINE_PER_CPU(__u32 [MD5_DIGEST_WORDS], get_random_int_hash);
 unsigned int get_random_int(void)
 {
 	__u32 *hash;
-- 
2.5.0