linux-kernel - [PATCH 3.12 079/100] random: properly align get_random_int

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Message-Id: <f9829334f4316454b675ac225daa24823e37c4d9.1471589700.git.jslaby@suse.cz>
Date:   Fri, 19 Aug 2016 09:11:18 +0200
From:   Jiri Slaby <jslaby@...e.cz>
To:     stable@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, Eric Biggers <ebiggers3@...il.com>,
        Theodore Ts'o <tytso@....edu>, Jiri Slaby <jslaby@...e.cz>
Subject: [PATCH 3.12 079/100] random: properly align get_random_int_hash

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

3.12-stable review patch.  If anyone has any objections, please let me know.

===============

commit b1132deac01c2332d234fa821a70022796b79182 upstream.

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>
Signed-off-by: Theodore Ts'o <tytso@....edu>
Signed-off-by: Jiri Slaby <jslaby@...e.cz>
---
 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 f6b25db16791..85e771c26488 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -1465,13 +1465,15 @@ 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;
-- 
2.9.3