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SubjectRe: [RESEND] [PATCH] Revert "efi/random: Treat EFI_RNG_PROTOCOL output as bootloader randomness"
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Hi,

> On 13 Oct 2021, at 10:50, Ard Biesheuvel <ardb@kernel.org> wrote:
>
> On Wed, 13 Oct 2021 at 09:30, Ivan T. Ivanov <iivanov@suse.de> wrote:
>>
>> Hi,
>>
>> Quoting Dominik Brodowski (2021-10-12 11:40:34)
>>> Am Tue, Oct 12, 2021 at 11:27:08AM +0300 schrieb Ivan T. Ivanov:
>>>> This reverts commit 18b915ac6b0ac5ba7ded03156860f60a9f16df2b.
>>>>
>>>> When CONFIG_RANDOM_TRUST_BOOTLOADER is enabled add_bootloader_randomness()
>>>> calls add_hwgenerator_randomness() which might sleep,
>>>
>>> Wouldn't it be better to fix add_bootloader_randomness(), considering
>>> that
>>> calls to that function are likely to happen quite early during kernel
>>> initialization? Especially as it seems to have worked beforehand?
>>
>> I have tried. I made wait_event_interruptible() optional, but then
>> crng_reseed() segfault badly. And I don't think crng_reseed() is
>> something that I could fix easily. Suggestions are welcomed ;-)
>>
>
> How about
>
> diff --git a/drivers/char/random.c b/drivers/char/random.c
> index 605969ed0f96..1828dc691ebf 100644
> --- a/drivers/char/random.c
> +++ b/drivers/char/random.c
> @@ -2297,9 +2297,8 @@ EXPORT_SYMBOL_GPL(add_hwgenerator_randomness);
> */
> void add_bootloader_randomness(const void *buf, unsigned int size)
> {
> + add_device_randomness(buf, size);
> if (IS_ENABLED(CONFIG_RANDOM_TRUST_BOOTLOADER))
> - add_hwgenerator_randomness(buf, size, size * 8);
> - else
> - add_device_randomness(buf, size);
> + credit_entropy(&input_pool, size * 8);
> }
> EXPORT_SYMBOL_GPL(add_bootloader_randomness);

This doesn’t boot. I just changed following and kernel panics.

- credit_entropy
+ credit_entropy_bits

Please see attached file.

Regards,
Ivan



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