linux-kernel - Re: [PATCH] mm: avoid zeroing user movable page twice with init_on

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: <f64f8a9e-fda8-4f7a-85a2-0113de2feb6c@suse.cz>
Date: Wed, 4 Dec 2024 16:41:12 +0100
From: Vlastimil Babka <vbabka@...e.cz>
To: Zi Yan <ziy@...dia.com>, Geert Uytterhoeven <geert@...ux-m68k.org>
Cc: linux-mm@...ck.org, Andrew Morton <akpm@...ux-foundation.org>,
 David Hildenbrand <david@...hat.com>,
 "Matthew Wilcox (Oracle)" <willy@...radead.org>,
 Miaohe Lin <linmiaohe@...wei.com>, Kefeng Wang <wangkefeng.wang@...wei.com>,
 John Hubbard <jhubbard@...dia.com>, "Huang, Ying" <ying.huang@...el.com>,
 Ryan Roberts <ryan.roberts@....com>, Alexander Potapenko
 <glider@...gle.com>, Kees Cook <keescook@...omium.org>,
 linux-kernel@...r.kernel.org, linux-mips@...r.kernel.org
Subject: Re: [PATCH] mm: avoid zeroing user movable page twice with
 init_on_alloc=1

On 12/4/24 16:24, Zi Yan wrote:
> On 4 Dec 2024, at 5:41, Geert Uytterhoeven wrote:
> 
> The provided config does not have THP on, so the changes to mm/huge_memory.c
> and mm/memory.c do not apply.
> 
> Can you try the patch below and see if the machine boots? Thanks.

Hmm looks like mips has some involved clear_user_page()
in arch/mips/include/asm/page.h

So maybe the clearing done as part of page allocator isn't enough here.

> 
> diff --git a/include/linux/highmem.h b/include/linux/highmem.h
> index 6e452bd8e7e3..bec9bd715acf 100644
> --- a/include/linux/highmem.h
> +++ b/include/linux/highmem.h
> @@ -224,7 +224,13 @@ static inline
>  struct folio *vma_alloc_zeroed_movable_folio(struct vm_area_struct *vma,
>  				   unsigned long vaddr)
>  {
> -	return vma_alloc_folio(GFP_HIGHUSER_MOVABLE | __GFP_ZERO, 0, vma, vaddr);
> +	struct folio *folio;
> +
> +	folio = vma_alloc_folio(GFP_HIGHUSER_MOVABLE, 0, vma, vaddr);
> +	if (folio)
> +		clear_user_highpage(&folio->page, vaddr);
> +
> +	return folio;
>  }
>  #endif
> 
> 
> Best Regards,
> Yan, Zi
>