From: "H. Peter Anvin" <hpa@zytor.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: "Ted Ts'o" <tytso@mit.edu>, DJ Johnston <dj.johnston@intel.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
"H. Peter Anvin" <hpa@linux.intel.com>,
stable <stable@vger.kernel.org>
Subject: Re: [PATCH 2/2] random: Account for entropy loss due to overwrites
Date: Thu, 25 Apr 2013 07:44:17 -0700 [thread overview]
Message-ID: <51794141.3070205@zytor.com> (raw)
In-Reply-To: <CA+55aFwkEMAkvZFdeQm2PKQD1xgFBfVa+kTwJXGmWXoDqDp7xQ@mail.gmail.com>
On 04/25/2013 07:38 AM, Linus Torvalds wrote:
> This doesn't work AT ALL. You even hint at the reason why in your message.
>
> On Tue, Apr 23, 2013 at 9:26 PM, H. Peter Anvin <hpa@zytor.com> wrote:
>>
>> As such, this conservatism seems more than justified. Note, however,
>> that attempting to add one bit of entropy will never succeed; nor will
>> two bits unless the pool is completely empty. These roundoff
>> artifacts could be improved by using fixed-point arithmetic and adding
>> some number of fractional entropy bits.
>
> Take a look at "add_interrupt_randomness()". Hmm..
>
<facepalm>
Right. Before July of last year add_interrupt_randomness() called
add_timer_randomness() which credits up to 11 bits, but not anymore.
-ESTALEBRAIN.
OK, so we need to track fractional bits.
-hpa
next prev parent reply other threads:[~2013-04-25 14:44 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1366777569-23192-1-git-send-email-hpa@zytor.com>
2013-04-24 4:26 ` [PATCH 1/2] random: Statically compute poolbitshift, poolbytes, poolbits H. Peter Anvin
2013-04-24 4:26 ` [PATCH 2/2] random: Account for entropy loss due to overwrites H. Peter Anvin
2013-04-25 14:38 ` Linus Torvalds
2013-04-25 14:44 ` H. Peter Anvin [this message]
2013-04-25 14:50 ` H. Peter Anvin
2013-04-25 15:19 ` H. Peter Anvin
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