linux-kernel - Re: [PATCH 0/2] x86/rdrand: implement sanity check for RDSEED

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <20250414115208.GCZ_z26G-_udwdX8JD@fat_crate.local>
Date: Mon, 14 Apr 2025 13:52:08 +0200
From: Borislav Petkov <bp@...en8.de>
To: Mikhail Paulyshka <me@...aill.net>
Cc: Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>,
	Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/2] x86/rdrand: implement sanity check for RDSEED

On Wed, Mar 12, 2025 at 03:31:28PM +0300, Mikhail Paulyshka wrote:
> On the AMD Cyan Skillfish (Family 0x17 Model 0x47 Stepping 0x0), which 
> is a Zen2-based APU found on the AMD BC-250 board, there is a situation 
> where RDRAND works fine, but RDSEED generates FF. This leads to some 

Ok, sorry, it took a bit longer than expected.

Your patch should simply disable RDSEED in CPUID on that family, model,
stepping CPUs. No need for the RDSEED sanity check.

So feel free to send v2.

I was gonna say, for extra points you could use CPUID faulting and completely
shield off userspace from that RDSEED but your CPU doesn't support it.

:-)

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette