linux-kernel - Re: [PATCH RESEND] lib/test_printf.c: call wait_for_random

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Date:   Tue, 5 Jun 2018 15:43:22 +0300
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Thierry Escande <thierry.escande@...aro.org>,
        Petr Mladek <pmladek@...e.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        David Miller <davem@...emloft.net>,
        Rasmus Villemoes <linux@...musvillemoes.dk>,
        "Tobin C . Harding" <me@...in.cc>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH RESEND] lib/test_printf.c: call wait_for_random_bytes()
 before plain %p tests

+Cc: Petr. I suppose test_printf is going through his tree as well as
vsnprintf itself. At least it logically makes sense.

On Mon, Jun 4, 2018 at 2:37 PM, Thierry Escande
<thierry.escande@...aro.org> wrote:
> If the test_printf module is loaded before the crng is initialized, the
> plain 'p' tests will fail because the printed address will not be hashed
> and the buffer will contain '(ptrval)' instead.
> This patch adds a call to wait_for_random_bytes() before plain 'p' tests
> to make sure the crng is initialized.
>
> Signed-off-by: Thierry Escande <thierry.escande@...aro.org>
> Acked-by: Tobin C. Harding <me@...in.cc>
> ---
>  lib/test_printf.c | 7 +++++++
>  1 file changed, 7 insertions(+)
>
> diff --git a/lib/test_printf.c b/lib/test_printf.c
> index 71ebfa43ad05..839be9385a8a 100644
> --- a/lib/test_printf.c
> +++ b/lib/test_printf.c
> @@ -260,6 +260,13 @@ plain(void)
>  {
>         int err;
>
> +       /*
> +        * Make sure crng is ready. Otherwise we get "(ptrval)" instead
> +        * of a hashed address when printing '%p' in plain_hash() and
> +        * plain_format().
> +        */
> +       wait_for_random_bytes();
> +
>         err = plain_hash();
>         if (err) {
>                 pr_warn("plain 'p' does not appear to be hashed\n");
> --
> 2.14.1
>



-- 
With Best Regards,
Andy Shevchenko