Messages in this thread | | | Date | Thu, 15 Aug 2019 01:38:49 +0200 | From | Pavel Machek <> | Subject | Re: Non-random RDRAND Re: [PATCH] x86/CPU/AMD: Clear RDRAND CPUID bit on AMD family 15h/16h |
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On Thu 2019-08-15 01:24:35, Pavel Machek wrote: > On Wed 2019-08-14 21:17:41, Lendacky, Thomas wrote: > > From: Tom Lendacky <thomas.lendacky@amd.com> > > > > There have been reports of RDRAND issues after resuming from suspend on > > some AMD family 15h and family 16h systems. This issue stems from BIOS > > not performing the proper steps during resume to ensure RDRAND continues > > to function properly. > > Burn it with fire! > > I mean... people were afraid RDRAND would be backdoored, and you now > confirm ... it indeed _is_ backdoored? /., here's news for you! > > So what is the impact? Does it give random-looking but predictable > numbers after resume? Does it give all zeros? Something else?
Plus... We trust the RDRAND in some configurations:
random.trust_cpu={on,off} [KNL] Enable or disable trusting the use of the CPU's random number generator (if available) to fully seed the kernel's CRNG. Default is controlled by CONFIG_RANDOM_TRUST_CPU.
so.. does this mean /dev/random was giving non-random values for some users?
Certainly it means userland users were getting non-random values. That sounds like something worth CVE and informing affected users?
Best regards, Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html [unhandled content-type:application/pgp-signature] | |