From: Andrew Morton <akpm@linux-foundation.org>
To: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: Kees Cook <keescook@chromium.org>,
linux-mm@kvack.org, linux-hardening@vger.kernel.org
Subject: Re: [PATCH 1/4] mm/usercopy: Check kmap addresses properly
Date: Mon, 9 May 2022 20:37:42 -0700 [thread overview]
Message-ID: <20220509203742.0f4adfa4004e51e66c1c9a20@linux-foundation.org> (raw)
In-Reply-To: <20220110231530.665970-2-willy@infradead.org>
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?
> no matter what the size of the underlying
> allocation. You can't kmap() a slab page because slab pages always
> come from low memory.
Why not? kmap() does
if (!PageHighMem(page))
addr = page_address(page);
else
addr = kmap_high(page);
next prev parent reply other threads:[~2022-05-10 3:37 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 [this message]
2022-05-10 22:01 ` Kees Cook
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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20220509203742.0f4adfa4004e51e66c1c9a20@linux-foundation.org \
--to=akpm@linux-foundation.org \
--cc=keescook@chromium.org \
--cc=linux-hardening@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=willy@infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).