linux-kernel - Re: CVE-2024-46839: workqueue: Improve scalability of workqueue watchdog touch

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Message-ID: <2024100116-shaky-iguana-7f54@gregkh>
Date: Tue, 1 Oct 2024 10:22:51 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: Petr Mladek <pmladek@...e.com>
Cc: cve@...nel.org, linux-kernel@...r.kernel.org,
	linux-cve-announce@...r.kernel.org,
	Srikar Dronamraju <srikar@...ux.vnet.ibm.com>,
	Nicholas Piggin <npiggin@...il.com>,
	"Paul E. McKenney" <paulmck@...nel.org>, Tejun Heo <tj@...nel.org>,
	Sasha Levin <sashal@...nel.org>, Michal Hocko <mhocko@...e.com>,
	Michal Koutný <mkoutny@...e.com>
Subject: Re: CVE-2024-46839: workqueue: Improve scalability of workqueue
 watchdog touch

On Tue, Oct 01, 2024 at 10:02:02AM +0200, Petr Mladek wrote:
> On Fri 2024-09-27 14:40:07, Greg Kroah-Hartman wrote:
> > Description
> > ===========
> > 
> > In the Linux kernel, the following vulnerability has been resolved:
> > 
> > workqueue: Improve scalability of workqueue watchdog touch
> > 
> > On a ~2000 CPU powerpc system, hard lockups have been observed in the
> > workqueue code when stop_machine runs (in this case due to CPU hotplug).
> 
> I believe that this does not qualify as a security vulnerability.
> Any hotplug is a privileged operation.

Really?  I see that happen on many embedded systems all the time, they
add/remove CPUs while the device runs/sleeps constantly.

Now to be fair, right now an "embedded system" usually doesn't have 2000
cpus, but what's wrong with marking this real bugfix as a vulnerability
resolution?  If you don't run your system in a way that allows cpus to
be stopped unless an admin says so, it will not be relevant.

thanks,

greg k-h