linux-kernel - Re: [tip: x86/bugs] x86/srso: Fix vulnerability reporting for missing microcode

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Message-ID: <20230901094053.GDZPGxpcG56GwE0LyG@fat_crate.local>
Date:   Fri, 1 Sep 2023 11:40:53 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Ingo Molnar <mingo@...nel.org>,
        Josh Poimboeuf <jpoimboe@...nel.org>
Cc:     linux-tip-commits@...r.kernel.org,
        Josh Poimboeuf <jpoimboe@...nel.org>,
        Ingo Molnar <mingo@...nel.org>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [tip: x86/bugs] x86/srso: Fix vulnerability reporting for
 missing microcode

On Fri, Aug 25, 2023 at 10:19:32AM -0000, tip-bot2 for Josh Poimboeuf wrote:
> The following commit has been merged into the x86/bugs branch of tip:
> 
> Commit-ID:     b3be1397be0340b2c30b2dcd7339dbfaa5563e2b
> Gitweb:        https://git.kernel.org/tip/b3be1397be0340b2c30b2dcd7339dbfaa5563e2b
> Author:        Josh Poimboeuf <jpoimboe@...nel.org>
> AuthorDate:    Fri, 25 Aug 2023 00:01:41 -07:00
> Committer:     Ingo Molnar <mingo@...nel.org>
> CommitterDate: Fri, 25 Aug 2023 11:21:59 +02:00
> 
> x86/srso: Fix vulnerability reporting for missing microcode
> 
> The SRSO default safe-ret mitigation is reported as "mitigated" even if
> microcode hasn't been updated.  That's wrong because userspace may still
> be vulnerable to SRSO attacks due to IBPB not flushing branch type
> predictions.
> 
> Report the safe-ret + !microcode case as vulnerable.
> 
> Also report the microcode-only case as vulnerable as it leaves the
> kernel open to attacks.
> 
> Fixes: fb3bd914b3ec ("x86/srso: Add a Speculative RAS Overflow mitigation")
> Signed-off-by: Josh Poimboeuf <jpoimboe@...nel.org>
> Signed-off-by: Ingo Molnar <mingo@...nel.org>
> Link: https://lore.kernel.org/r/65556eeb1bf7cb9bd7db8662ef115dd73191db84.1692919072.git.jpoimboe@kernel.org
> ---
>  Documentation/admin-guide/hw-vuln/srso.rst | 22 ++++++++++----
>  arch/x86/kernel/cpu/bugs.c                 | 34 ++++++++++++---------
>  2 files changed, 37 insertions(+), 19 deletions(-)

This is still unfixed:

https://lore.kernel.org/r/20230825072542.GFZOhXdgXpUidW51lC@fat_crate.local

mingo, do you want fixes ontop or do you wanna rebase this branch?

Thx.

-- 
Regards/Gruss,
    Boris.

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