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Date:   Thu, 20 Jan 2022 19:04:26 +0000
From:   Matthew Wilcox <willy@infradead.org>
To:     "Russell King (Oracle)" <linux@armlinux.org.uk>
Cc:     Robin Murphy <robin.murphy@arm.com>,
        Yury Norov <yury.norov@gmail.com>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Nicholas Piggin <npiggin@gmail.com>,
        Ding Tianhong <dingtianhong@huawei.com>,
        Anshuman Khandual <anshuman.khandual@arm.com>,
        Alexey Klimov <aklimov@redhat.com>,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        linux-mm@kvack.org
Subject: Re: [PATCH] vmap(): don't allow invalid pages
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On Thu, Jan 20, 2022 at 04:54:03PM +0000, Russell King (Oracle) wrote:
> Well, I think I've adequately explained why I believe:
> 
> 	pfn_is_valid(page_to_pfn(page))
> 
> being used as the primary check is substandard, and will likely lead to
> a future CVE. When generating an array of struct page's, I believe that
> it is the responsibility for the generator to ensure that the array
> only contains valid pages.

So you're saying that virt_to_page() should be made more expensive?