From: David Hildenbrand <david@redhat.com>
To: Ruihan Li <lrh2000@pku.edu.cn>,
linux-mm@kvack.org, linux-usb@vger.kernel.org
Cc: linux-kernel@vger.kernel.org,
Pasha Tatashin <pasha.tatashin@soleen.com>,
Matthew Wilcox <willy@infradead.org>,
Andrew Morton <akpm@linux-foundation.org>,
Christoph Hellwig <hch@infradead.org>,
Alan Stern <stern@rowland.harvard.edu>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
stable@vger.kernel.org
Subject: Re: [PATCH v2 3/4] mm: page_table_check: Make it dependent on EXCLUSIVE_SYSTEM_RAM
Date: Tue, 16 May 2023 14:55:01 +0200 [thread overview]
Message-ID: <72fc50da-c3b9-b71b-209b-9413a8693f13@redhat.com> (raw)
In-Reply-To: <20230515130958.32471-4-lrh2000@pku.edu.cn>
On 15.05.23 15:09, Ruihan Li wrote:
> Without EXCLUSIVE_SYSTEM_RAM, users are allowed to map arbitrary
> physical memory regions into the userspace via /dev/mem. At the same
> time, pages may change their properties (e.g., from anonymous pages to
> named pages) while they are still being mapped in the userspace, leading
> to "corruption" detected by the page table check.
>
> To avoid these false positives, this patch makes PAGE_TABLE_CHECK
> depends on EXCLUSIVE_SYSTEM_RAM. This dependency is understandable
> because PAGE_TABLE_CHECK is a hardening technique but /dev/mem without
> STRICT_DEVMEM (i.e., !EXCLUSIVE_SYSTEM_RAM) is itself a security
> problem.
>
> Even with EXCLUSIVE_SYSTEM_RAM, I/O pages may be still allowed to be
> mapped via /dev/mem. However, these pages are always considered as named
> pages, so they won't break the logic used in the page table check.
>
> Cc: <stable@vger.kernel.org> # 5.17
> Signed-off-by: Ruihan Li <lrh2000@pku.edu.cn>
Acked-by: David Hildenbrand <david@redhat.com>
--
Thanks,
David / dhildenb
next prev parent reply other threads:[~2023-05-16 12:55 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20230515130958.32471-1-lrh2000@pku.edu.cn>
2023-05-15 13:09 ` [PATCH v2 1/4] usb: usbfs: Enforce page requirements for mmap Ruihan Li
2023-05-15 14:07 ` Alan Stern
2023-05-17 6:22 ` Christoph Hellwig
2023-05-15 13:09 ` [PATCH v2 2/4] usb: usbfs: Use consistent mmap functions Ruihan Li
2023-05-15 16:07 ` David Laight
2023-05-16 11:42 ` Ruihan Li
2023-05-15 13:09 ` [PATCH v2 3/4] mm: page_table_check: Make it dependent on EXCLUSIVE_SYSTEM_RAM Ruihan Li
2023-05-15 16:36 ` Pasha Tatashin
2023-05-16 12:55 ` David Hildenbrand [this message]
2023-05-15 13:09 ` [PATCH v2 4/4] mm: page_table_check: Ensure user pages are not slab pages Ruihan Li
2023-05-15 16:28 ` Pasha Tatashin
2023-05-16 11:51 ` Ruihan Li
2023-05-16 12:54 ` David Hildenbrand
2023-05-16 14:14 ` Pasha Tatashin
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