linux-kernel - Re: [PATCH] mips: allow firmware to pass RNG seed to kernel

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Message-ID: <CAHmME9pbVUxTJrF-2XRHsz07P127TyvEWbDL38hi2YdRry+pAQ@mail.gmail.com>
Date:   Tue, 4 Oct 2022 00:30:25 +0200
From:   "Jason A. Donenfeld" <Jason@...c4.com>
To:     Philippe Mathieu-Daudé <f4bug@...at.org>
Cc:     Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        "open list:BROADCOM NVRAM DRIVER" <linux-mips@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] mips: allow firmware to pass RNG seed to kernel

Hi Philippe,

On Tue, Oct 4, 2022 at 12:07 AM Philippe Mathieu-Daudé <f4bug@...at.org> wrote:
> > +       add_bootloader_randomness(rng_seed, len);
>
> So we call char/random code with len=0. Is it safe?
> Maybe simply safer to check len before calling hex2bin?

add_bootloader_randomness() is safe for all input sizes, and is
written to be callable with len=0 and have no effect. So this function
should be good as-is; there's no need to special case an unlikely
instance that's already handled by add_bootloader_randomness().

Jason