linux-kernel - [PATCH] random: properly align get_random_int

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Message-Id: <1459473085-10724-1-git-send-email-ebiggers3@gmail.com>
Date:	Thu, 31 Mar 2016 20:11:25 -0500
From:	Eric Biggers <ebiggers3@...il.com>
To:	linux-kernel@...r.kernel.org
Cc:	arnd@...db.de, gregkh@...uxfoundation.org, tytso@....edu,
	Eric Biggers <ebiggers3@...il.com>
Subject: [PATCH] random: properly align get_random_int_hash

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.

Signed-off-by: Eric Biggers <ebiggers3@...il.com>
---
 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 b583e53..f867ef4 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -1792,13 +1792,15 @@ 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;
-- 
2.7.4