linux-kernel - Re: [PATCH] x86/bugs: Don't warn when overwriting retbleed_return_thunk with srso_return

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]

Message-ID: <20250515173830.uulahmrm37vyjopx@desk>
Date: Thu, 15 May 2025 10:38:30 -0700
From: Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>
To: Borislav Petkov <bp@...en8.de>
Cc: Suraj Jitindar Singh <surajjs@...zon.com>, linux-kernel@...r.kernel.org,
	x86@...nel.org, Thomas Gleixner <tglx@...utronix.de>,
	Peter Zijlstra <peterz@...radead.org>,
	Josh Poimboeuf <jpoimboe@...nel.org>,
	Ingo Molnar <mingo@...hat.com>,
	Dave Hansen <dave.hansen@...ux.intel.com>, stable@...r.kernel.org
Subject: Re: [PATCH] x86/bugs: Don't warn when overwriting
 retbleed_return_thunk with srso_return_thunk

On Thu, May 15, 2025 at 07:23:55PM +0200, Borislav Petkov wrote:
> On Thu, May 15, 2025 at 10:06:33AM -0700, Pawan Gupta wrote:
> > As I said above, a mitigation unintentionally make another mitigation
> > ineffective.
> 
> I actually didn't need an analysis - my point is: if you're going to warn
> about it, then make it big so that it gets caught.
> 
> > Yes, maybe a WARN_ON() conditional to sanity checks for retbleed/SRSO.
> 
> Yes, that.
> 
> At least.
> 
> The next step would be if this whole "let's set a thunk without overwriting
> a previously set one" can be fixed differently.
> 
> For now, though, the *least* what should be done here is catch the critical
> cases where a mitigation is rendered ineffective. And warning Joe Normal User
> about it doesn't bring anything. We do decide for the user what is safe or
> not, practically. At least this has been the strategy until now.
> 
> So the goal here should be to make Joe catch this and tell us to fix it.
> 
> Makes sense?

Absolutely makes sense.

Suraj, do want to revise this patch? Or else I can do it too.