Fwd: AMD Geode LX hardware RNG driver produces regular patterns (geode-rng.c)

From: Bagas Sanjaya
Date: Thu Sep 07 2023 - 11:38:57 EST


Hi,

I notice a regression report on Bugzilla [1]. Quoting from it:

> System: Alix board 2d13 (AMD Geode LX800) running OpenWrt 23.05.0-rc3 (kernel 5.15.127)
>
> Steps to reproduce:
>
> cat /dev/hwrng and see output. Output in console shows regular pattern, rngd daemon (from rng-tools) refuses to run because of low entropy from /dev/hwrng. Pattern doesn't change until I reboot system.
>
> Important notice: This problem started somewhere between 4.14.267 (kernel used in OpenWrt 19.07.9) and my current 5.15.127.
>
> OpenWrt developers recommended addressing this problem upstream since they did not alter this driver in any way.

See Bugzilla for the full thread.

Anyway, I'm adding it to regzbot:

#regzbot ^introduced: v4.14.267..v5.15.127
#regzbot title: predictable urandom output on Alix 2d13

Thanks.

[1]: https://bugzilla.kernel.org/show_bug.cgi?id=217882

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