From: Kees Cook <keescook@chromium.org>
To: "Theodore Ts'o" <tytso@mit.edu>
Cc: Linux Kernel Developers List <linux-kernel@vger.kernel.org>,
ewust@umich.edu, zakir@umich.edu, nadiah@cs.ucsd.edu,
jhalderm@umich.edu, stable@vger.kernel.org
Subject: [PATCH] random: only use gathered bytes from arch_get_random_long
Date: Sat, 7 Jul 2012 10:11:22 -0700 [thread overview]
Message-ID: <20120707171122.GD28340@outflux.net> (raw)
In-Reply-To: <1341614704-24965-8-git-send-email-tytso@mit.edu>
While very unlikely, it is possible for arch_get_random_long() to fail
in the middle of the loop in xfer_secondary_pool(), which would mean
that the loop could stop with only part of u.hwrand populated, leading
to mix_pool_bytes() injecting uninitialized or already injected bytes
instead of fresh bytes. This changes the mix_pool_bytes() call to only
inject the successfully gathered bytes.
Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: stable@vger.kernel.org
---
Should be applied on top of the tytso/random dev branch.
---
drivers/char/random.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/drivers/char/random.c b/drivers/char/random.c
index aaf4629..6fc3128 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -879,7 +879,7 @@ static void xfer_secondary_pool(struct entropy_store *r, size_t nbytes)
if (arch_get_random_long(&u.hwrand[i]))
break;
if (i)
- mix_pool_bytes(r, &u.hwrand, sizeof(u.hwrand), 0);
+ mix_pool_bytes(r, &u.hwrand, i * sizeof(u.hwrand[0]), 0);
}
/*
--
1.7.0.4
--
Kees Cook
Chrome OS Security
next prev parent reply other threads:[~2012-07-07 17:11 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-06 22:44 [PATCH 00/12] /dev/random fixups Theodore Ts'o
2012-07-06 22:44 ` [PATCH 01/12] random: fix up sparse warnings Theodore Ts'o
2012-07-06 22:44 ` [PATCH 02/12] random: make 'add_interrupt_randomness()' do something sane Theodore Ts'o
2012-07-08 2:01 ` Ben Hutchings
2012-07-06 22:44 ` [PATCH 03/12] random: use lockless techniques in the interrupt path Theodore Ts'o
2012-07-06 22:44 ` [PATCH 04/12] random: create add_device_randomness() interface Theodore Ts'o
2012-07-06 22:44 ` [PATCH 05/12] usb: feed USB device information to the /dev/random driver Theodore Ts'o
2012-07-06 23:02 ` Jonathan Nieder
2012-07-06 23:18 ` Greg KH
2012-07-06 23:26 ` Theodore Ts'o
2012-07-07 1:08 ` Jonathan Nieder
2012-07-06 22:44 ` [PATCH 06/12] net: feed /dev/random with the MAC address when registering a device Theodore Ts'o
2012-07-06 22:44 ` [PATCH 07/12] random: use the arch-specific rng in xfer_secondary_pool Theodore Ts'o
2012-07-07 17:11 ` Kees Cook [this message]
2012-07-07 18:23 ` [PATCH] random: only use gathered bytes from arch_get_random_long Theodore Ts'o
2012-07-07 23:20 ` Kees Cook
2012-07-08 1:06 ` [PATCH 07/12] random: use the arch-specific rng in xfer_secondary_pool Ben Hutchings
2012-07-08 1:41 ` Theodore Ts'o
2012-07-08 2:06 ` Ben Hutchings
2012-07-06 22:45 ` [PATCH 08/12] random: add new get_random_bytes_arch() function Theodore Ts'o
2012-07-06 22:45 ` [PATCH 09/12] random: add tracepoints for easier debugging and verification Theodore Ts'o
2012-07-06 22:45 ` [PATCH 10/12] MAINTAINERS: Theodore Ts'o is taking over the random driver Theodore Ts'o
2012-07-06 22:45 ` [PATCH 11/12] rtc: wm831x: Feed the write counter into device_add_randomness() Theodore Ts'o
2012-07-06 22:45 ` [PATCH 12/12] mfd: wm831x: Feed the device UUID " Theodore Ts'o
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