linux-kernel - Re: RETBleed: WARNING: Spectre v2 mitigation leaves CPU vulnerable to RETBleed attacks, data leaks possible!

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Message-ID: <20220715221901.xm3c4w4idqt67uja@desk>
Date:   Fri, 15 Jul 2022 15:19:01 -0700
From:   Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Naresh Kamboju <naresh.kamboju@...aro.org>,
        open list <linux-kernel@...r.kernel.org>,
        X86 ML <x86@...nel.org>, lkft-triage@...ts.linaro.org,
        Borislav Petkov <bp@...e.de>,
        Peter Zijlstra <peterz@...radead.org>,
        Josh Poimboeuf <jpoimboe@...nel.org>
Subject: Re: RETBleed: WARNING: Spectre v2 mitigation leaves CPU vulnerable
 to RETBleed attacks, data leaks possible!

On Thu, Jul 14, 2022 at 11:01:12AM +0200, Greg Kroah-Hartman wrote:
> On Thu, Jul 14, 2022 at 02:15:07PM +0530, Naresh Kamboju wrote:
> > Results from Linaro’s test farm.
> > 
> > We are booting the i386 kernel on an x86 machine.
> > With Spectre V2 patches merged into Linux mainline we have been noticing
> > RETBleed: WARNING: Spectre v2 mitigation leaves CPU vulnerable to
> > RETBleed attacks, data leaks possible!
> 
> That's funny.  I don't think that's a valid combination that should be
> cared about, but I'll leave it to Pawan to comment if it is something
> that is "real" to be concerned for.

Intel is not aware of production environments that use 32-bit mode on
Skylake-gen CPUs. So this should not be a concern.

Thanks,
Pawan