linux-kernel - Re: [PATCH RFC 33/35] kfence: drop nth

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: <1a13a5cb-4312-4c01-827b-fa8a029df0f1@redhat.com>
Date: Thu, 21 Aug 2025 22:32:29 +0200
From: David Hildenbrand <david@...hat.com>
To: linux-kernel@...r.kernel.org
Cc: Alexander Potapenko <glider@...gle.com>, Marco Elver <elver@...gle.com>,
 Dmitry Vyukov <dvyukov@...gle.com>, Andrew Morton
 <akpm@...ux-foundation.org>, Brendan Jackman <jackmanb@...gle.com>,
 Christoph Lameter <cl@...two.org>, Dennis Zhou <dennis@...nel.org>,
 dri-devel@...ts.freedesktop.org, intel-gfx@...ts.freedesktop.org,
 iommu@...ts.linux.dev, io-uring@...r.kernel.org,
 Jason Gunthorpe <jgg@...dia.com>, Jens Axboe <axboe@...nel.dk>,
 Johannes Weiner <hannes@...xchg.org>, John Hubbard <jhubbard@...dia.com>,
 kasan-dev@...glegroups.com, kvm@...r.kernel.org,
 "Liam R. Howlett" <Liam.Howlett@...cle.com>,
 Linus Torvalds <torvalds@...ux-foundation.org>, linux-arm-kernel@...s.com,
 linux-arm-kernel@...ts.infradead.org, linux-crypto@...r.kernel.org,
 linux-ide@...r.kernel.org, linux-kselftest@...r.kernel.org,
 linux-mips@...r.kernel.org, linux-mmc@...r.kernel.org, linux-mm@...ck.org,
 linux-riscv@...ts.infradead.org, linux-s390@...r.kernel.org,
 linux-scsi@...r.kernel.org, Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
 Marek Szyprowski <m.szyprowski@...sung.com>, Michal Hocko <mhocko@...e.com>,
 Mike Rapoport <rppt@...nel.org>, Muchun Song <muchun.song@...ux.dev>,
 netdev@...r.kernel.org, Oscar Salvador <osalvador@...e.de>,
 Peter Xu <peterx@...hat.com>, Robin Murphy <robin.murphy@....com>,
 Suren Baghdasaryan <surenb@...gle.com>, Tejun Heo <tj@...nel.org>,
 virtualization@...ts.linux.dev, Vlastimil Babka <vbabka@...e.cz>,
 wireguard@...ts.zx2c4.com, x86@...nel.org, Zi Yan <ziy@...dia.com>
Subject: Re: [PATCH RFC 33/35] kfence: drop nth_page() usage

On 21.08.25 22:06, David Hildenbrand wrote:
> We want to get rid of nth_page(), and kfence init code is the last user.
> 
> Unfortunately, we might actually walk a PFN range where the pages are
> not contiguous, because we might be allocating an area from memblock
> that could span memory sections in problematic kernel configs (SPARSEMEM
> without SPARSEMEM_VMEMMAP).
> 
> We could check whether the page range is contiguous
> using page_range_contiguous() and failing kfence init, or making kfence
> incompatible these problemtic kernel configs.
> 
> Let's keep it simple and simply use pfn_to_page() by iterating PFNs.
> 

Fortunately this series is RFC due to lack of detailed testing :P

Something gives me a NULL-pointer pointer here (maybe the virt_to_phys()).

Will look into that tomorrow.

-- 
Cheers

David / dhildenb