linux-kernel - Re: [patch V3 56/66] x86/fpu: Dont store PKRU in xstate in fpu_reset

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

Date:   Tue, 22 Jun 2021 19:10:15 +0200
From:   Borislav Petkov <bp@...e.de>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Andy Lutomirski <luto@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Fenghua Yu <fenghua.yu@...el.com>,
        Tony Luck <tony.luck@...el.com>,
        Yu-cheng Yu <yu-cheng.yu@...el.com>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        Peter Zijlstra <peterz@...radead.org>,
        Kan Liang <kan.liang@...ux.intel.com>
Subject: Re: [patch V3 56/66] x86/fpu: Dont store PKRU in xstate in
 fpu_reset_fpstate()

On Fri, Jun 18, 2021 at 04:19:19PM +0200, Thomas Gleixner wrote:
> PKRU for a task is stored in task->thread.pkru when the task is scheduled
> out. For 'current' the authoritative source of PKRU is the hardware.
> 
> fpu_reset_fpstate() has two callers:
> 
>   1) fpu__clear_user_states() for !FPU systems. For those PKRU is irrelevant
> 
>   2) fpu_flush_thread() which is invoked from flush_thread(). flush_thread()
>      resets the hardware to the kernel restrictive default value.
> 
> Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
> ---
>  arch/x86/kernel/fpu/core.c |   22 ++++------------------
>  1 file changed, 4 insertions(+), 18 deletions(-)

Reviewed-by: Borislav Petkov <bp@...e.de>

-- 
Regards/Gruss,
    Boris.

SUSE Software Solutions Germany GmbH, GF: Felix Imendörffer, HRB 36809, AG Nürnberg