From: Kees Cook <keescook@chromium.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>,
linux-mm@kvack.org, linux-hardening@vger.kernel.org
Subject: Re: [PATCH 1/4] mm/usercopy: Check kmap addresses properly
Date: Tue, 10 May 2022 15:01:22 -0700 [thread overview]
Message-ID: <202205101455.24F5C046F@keescook> (raw)
In-Reply-To: <20220509203742.0f4adfa4004e51e66c1c9a20@linux-foundation.org>
On Mon, May 09, 2022 at 08:37:42PM -0700, Andrew Morton wrote:
> On Mon, 10 Jan 2022 23:15:27 +0000 "Matthew Wilcox (Oracle)" <willy@infradead.org> wrote:
>
> > If you are copying to an address in the kmap region, you may not copy
> > across a page boundary,
>
> In the source, the destination or in both, and why may we not?
This depends on direction. For copying to userspace, the source (kmap).
For copying from userspace, the destination (kmap).
> > no matter what the size of the underlying
> > allocation. You can't kmap() a slab page because slab pages always
> > come from low memory.
As in it'll be processed as a slab page instead of kmap by the usercopy
checks?
--
Kees Cook
next prev parent reply other threads:[~2022-05-10 22:01 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-10 23:15 [PATCH 0/4] Assorted improvements to usercopy Matthew Wilcox (Oracle)
2022-01-10 23:15 ` [PATCH 1/4] mm/usercopy: Check kmap addresses properly Matthew Wilcox (Oracle)
2022-05-10 3:37 ` Andrew Morton
2022-05-10 22:01 ` Kees Cook [this message]
2022-01-10 23:15 ` [PATCH 2/4] mm/usercopy: Detect vmalloc overruns Matthew Wilcox (Oracle)
2022-01-10 23:15 ` [PATCH 3/4] mm/usercopy: Detect large folio overruns Matthew Wilcox (Oracle)
2022-01-31 14:28 ` David Hildenbrand
2022-01-10 23:15 ` [PATCH 4/4] usercopy: Remove HARDENED_USERCOPY_PAGESPAN Matthew Wilcox (Oracle)
2022-01-12 23:08 ` Kees Cook
2022-01-31 14:27 ` David Hildenbrand
2022-01-31 19:27 ` Matthew Wilcox
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