linux-kernel - Re: [PATCH v6 2/8] mm,memory_hotplug: Relax fully spanned sections check

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: <df9bdb5157d6ad2f4a922d396ddf0c07@suse.de>
Date:   Tue, 06 Apr 2021 18:33:59 +0200
From:   Oscar Salvador <osalvador@...e.de>
To:     David Hildenbrand <david@...hat.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Michal Hocko <mhocko@...nel.org>,
        Anshuman Khandual <anshuman.khandual@....com>,
        Pavel Tatashin <pasha.tatashin@...een.com>,
        Vlastimil Babka <vbabka@...e.cz>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v6 2/8] mm,memory_hotplug: Relax fully spanned sections
 check

On 2021-04-06 17:32, David Hildenbrand wrote:
> I'd only relax start_pfn. That way the function is pretty much
> impossible to abuse for sub-section onlining/offlining.
> 
> if (WARN_ON_ONCE(!nr_pages ||
> 		 !IS_ALIGNED(start_pfn, pageblock_nr_pages))
> 		 !IS_ALIGNED(start_pfn + nr_pages, PAGES_PER_SECTION)))

But this is not going to work.
When using memmap_on_memory, the nr of pages that online_pages() and 
offline_pages() get might be less than PAGES_PER_SECTION, so this check 
will always blow us up.

-- 
Oscar Salvador
SUSE L3