linux-kernel - Re: CVE-2021-47090: mm/hwpoison: clear MF_COUNT_INCREASED before retrying get_any

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Message-ID: <2024030541-unhappily-staff-8662@gregkh>
Date: Tue, 5 Mar 2024 22:20:17 +0000
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: Michal Hocko <mhocko@...e.com>
Cc: cve@...nel.org, linux-kernel@...r.kernel.org
Subject: Re: CVE-2021-47090: mm/hwpoison: clear MF_COUNT_INCREASED before
 retrying get_any_page()

On Tue, Mar 05, 2024 at 07:45:04PM +0100, Michal Hocko wrote:
> On Mon 04-03-24 19:11:17, Greg KH wrote:
> > Description
> > ===========
> > 
> > In the Linux kernel, the following vulnerability has been resolved:
> > 
> > mm/hwpoison: clear MF_COUNT_INCREASED before retrying get_any_page()
> 
> I would like to dispute this CVE. The interface is behind CAP_SYSADMIN
> and allowing access to this to any untrusted party is risking serious
> troubles. This is a testing only feature.

This fixes a weakness in the kernel, one that is allowed to crash it,
why isn't that a good thing to have a CVE entry for?  Are we saying that
all VM_BUG_ON_PAGE() instances should not be accounted for?  That's not
what the config option for CONFIG_DEBUG_VM says, it just says it will
affect performance.

Also /sys/devices/system/memory/soft_offline_page doesn't say "can crash
the system", so it should work properly, even if an admin uses it, it
shouldn't shut the box down.

confused,

greg k-h