Re: [PATCH 1/2] random32: make prandom_u32() output unpredictable

Sedat Dilek
2020-09-14T16:21:42Z

On Mon, Sep 14, 2020 at 4:53 PM Amit Klein <aksecurity@gmail.com> wrote:
>
> Hi
>
> Is this patch being pushed to any branch? I don't see it deployed anywhere (unless I'm missing something...).
>

It's here:

[1] https://git.kernel.org/pub/scm/linux/kernel/git/wtarreau/prandom.git/log/?h=20200901-siphash-noise

> Best,
> -Amit
>
>
>
> On Tue, Sep 1, 2020 at 4:16 PM Willy Tarreau <w@1wt.eu> wrote:
>>
>> On Tue, Sep 01, 2020 at 01:10:18PM +0000, David Laight wrote:
>> > From: Willy Tarreau
>> > > Sent: 01 September 2020 07:43
>> > ...
>> > > +/*
>> > > + * Generate some initially weak seeding values to allow
>> > > + * the prandom_u32() engine to be started.
>> > > + */
>> > > +static int __init prandom_init_early(void)
>> > > +{
>> > > + int i;
>> > > + unsigned long v0, v1, v2, v3;
>> > > +
>> > > + if (!arch_get_random_long(&v0))
>> > > + v0 = jiffies;
>> >
>> > Isn't jiffies likely to be zero here?
>>
>> I don't know. But do we really care ? I'd personally have been fine
>> with not even assigning it in this case and leaving whatever was in
>> the stack in this case, though it could make some static code analyzer
>> unhappy.
>>
>> Willy