linux-kernel - Re: [PATCH v2] x86/bugs: Fix use of possibly uninit value in amd_check_tsa

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Message-ID: <2025072906-poking-basket-93dc@gregkh>
Date: Tue, 29 Jul 2025 16:38:17 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: "Zhivich, Michael" <mzhivich@...mai.com>
Cc: Borislav Petkov <bp@...en8.de>,
	"stable@...r.kernel.org" <stable@...r.kernel.org>,
	"tglx@...utronix.de" <tglx@...utronix.de>,
	"mingo@...hat.com" <mingo@...hat.com>,
	"dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>,
	"x86@...nel.org" <x86@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] x86/bugs: Fix use of possibly uninit value in
 amd_check_tsa_microcode()

On Wed, Jul 23, 2025 at 01:47:58PM +0000, Zhivich, Michael wrote:
> 
> On 7/22/25, 12:56, "Greg Kroah-Hartman" <gregkh@...uxfoundation.org> wrote:
> 
> !-------------------------------------------------------------------|
>   This Message Is From an External Sender
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> 
> On Tue, Jul 22, 2025 at 04:22:54PM +0200, Borislav Petkov wrote:
> > On Tue, Jul 22, 2025 at 08:28:44AM -0400, Michael Zhivich wrote:
> > > For kernels compiled with CONFIG_INIT_STACK_NONE=y, the value of __reserved
> > > field in zen_patch_rev union on the stack may be garbage.  If so, it will
> > > prevent correct microcode check when consulting p.ucode_rev, resulting in
> > > incorrect mitigation selection.
> >
> > "This is a stable-only fix." so that the AI is happy. :-P
> >
> > > Cc: <stable@...r.kernel.org>
> > > Signed-off-by:  Michael Zhivich <mzhivich@...mai.com>
> >
> > Acked-by: Borislav Petkov (AMD) <bp@...en8.de>
> >
> > > Fixes: 7a0395f6607a5 ("x86/bugs: Add a Transient Scheduler Attacks mitigation")
> >
> > That commit in Fixes: is the 6.12 stable one.
> >
> > The 6.6 one is:
> >
> > Fixes: 90293047df18 ("x86/bugs: Add a Transient Scheduler Attacks mitigation")
> >
> > The 6.1 is:
> >
> > Fixes: d12145e8454f ("x86/bugs: Add a Transient Scheduler Attacks mitigation")
> >
> > The 5.15 one:
> >
> > Fixes: f2b75f1368af ("x86/bugs: Add a Transient Scheduler Attacks mitigation")
> >
> > and the 5.10 one is
> >
> > Fixes: 78192f511f40 ("x86/bugs: Add a Transient Scheduler Attacks mitigation")
> >
> > and since all stable kernels above have INIT_STACK_NONE, that same
> > one-liner should be applied to all of them.
> >
> > Greg, I'm thinking this one-liner should apply to all of the above with
> > some fuzz. Can you simply add it to each stable version with a different
> > Fixes: tag each?
> >
> > Or do you prefer separate submissions?
> 
> Ideally, separate submissions, otherwise I have to do this all by hand
> :(
> 
> thanks
> 
> greg k-h
> 
> Apologies for the barrage of e-mails; I managed to mess up the subject line on a couple, so I’ve resent them with correct subject lines.
> There’s now a submission per stable branch with appropriate patch and fixes tags.

Ok, I think I got them all figured out, thanks!

greg k-h