From: Kees Cook <keescook@chromium.org>
To: "Roberts, William C" <william.c.roberts@intel.com>,
Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mm@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>,
Russell King - ARM Linux <linux@arm.linux.org.uk>,
"Theodore Ts'o" <tytso@mit.edu>, Arnd Bergmann <arnd@arndb.de>,
Greg KH <gregkh@linuxfoundation.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will.deacon@arm.com>,
Ralf Baechle <ralf@linux-mips.org>,
"benh@kernel.crashing.org" <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>,
Michael Ellerman <mpe@ellerman.id.au>,
"David S. Miller" <davem@davemloft.net>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
"x86@kernel.org" <x86@kernel.org>,
Al Viro <viro@zeniv.linux.org.uk>,
Nick Kralevich <nnk@google.com>,
Jeffrey Vander Stoep <jeffv@google.com>,
Mark Salyzyn <salyzyn@android.com>,
Daniel Cashman <dcashman@android.com>
Subject: Re: [PATCH] randomize_range: use random long instead of int
Date: Mon, 25 Jul 2016 11:54:02 -0700 [thread overview]
Message-ID: <CAGXu5jLOk52XzQT9EA8vq5B3G3ks8Nmsfc6keA8kpG9LvaTE9Q@mail.gmail.com> (raw)
In-Reply-To: <1469471141-25669-1-git-send-email-william.c.roberts@intel.com>
On Mon, Jul 25, 2016 at 11:25 AM, <william.c.roberts@intel.com> wrote:
> From: William Roberts <william.c.roberts@intel.com>
>
> Use a long when generating the random range rather than
> an int. This will produce better random distributions as
> well as matching all the types at hand.
>
> Signed-off-by: William Roberts <william.c.roberts@intel.com>
I agree, this is what I pointed out back in Feb:
https://lkml.org/lkml/2016/2/4/854
Acked-by: Kees Cook <keescook@chromium.org>
Andrew, can you pick this up for 4.8?
-Kees
> ---
> drivers/char/random.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/char/random.c b/drivers/char/random.c
> index 0158d3b..bbf11b5 100644
> --- a/drivers/char/random.c
> +++ b/drivers/char/random.c
> @@ -1837,7 +1837,8 @@ randomize_range(unsigned long start, unsigned long end, unsigned long len)
>
> if (end <= start + len)
> return 0;
> - return PAGE_ALIGN(get_random_int() % range + start);
> +
> + return PAGE_ALIGN(get_random_long() % range + start);
> }
>
> /* Interface for in-kernel drivers of true hardware RNGs.
> --
> 1.9.1
>
--
Kees Cook
Chrome OS & Brillo Security
next prev parent reply other threads:[~2016-07-25 18:54 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-25 18:25 [PATCH] randomize_range: use random long instead of int william.c.roberts
2016-07-25 18:54 ` Kees Cook [this message]
2016-07-26 2:18 ` Jason Cooper
2016-07-26 3:01 ` [RFC patch 1/6] random: Simplify API for random address requests Jason Cooper
2016-07-26 3:01 ` [RFC patch 2/6] x86: Use simpler " Jason Cooper
2016-07-26 3:01 ` [RFC patch 3/6] ARM: " Jason Cooper
2016-07-26 3:01 ` [RFC patch 4/6] arm64: " Jason Cooper
2016-07-26 3:01 ` [RFC patch 5/6] tile: " Jason Cooper
2016-07-26 3:02 ` [RFC patch 6/6] unicore32: " Jason Cooper
2016-07-26 3:30 ` [RFC patch 1/6] random: Simplify " Jason Cooper
2016-07-26 4:39 ` Kees Cook
2016-07-26 17:00 ` Jason Cooper
2016-07-26 17:07 ` Kees Cook
2016-07-28 19:02 ` Jason Cooper
2016-07-26 17:33 ` Roberts, William C
2016-07-26 4:44 ` Kees Cook
2016-07-26 15:55 ` Jason Cooper
2016-07-26 16:40 ` Kees Cook
2016-07-27 13:51 ` [kernel-hardening] " Yann Droneaud
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