From: Linus Torvalds <torvalds@linux-foundation.org>
To: Rik van Riel <riel@redhat.com>
Cc: Hugh Dickins <hughd@google.com>,
Lorenzo Stoakes <lstoakes@gmail.com>,
linux-mm <linux-mm@kvack.org>,
Mel Gorman <mgorman@techsingularity.net>,
tbsaunde@tbsaunde.org, robert@ocallahan.org,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH] mm: check VMA flags to avoid invalid PROT_NONE NUMA balancing
Date: Sun, 25 Sep 2016 18:05:56 -0700 [thread overview]
Message-ID: <CA+55aFyP2Aw7ET5oNX9fB644PGKrguk-mhXdcEN_aHvnVVsUjg@mail.gmail.com> (raw)
In-Reply-To: <1474850960.17726.48.camel@redhat.com>
On Sun, Sep 25, 2016 at 5:49 PM, Rik van Riel <riel@redhat.com> wrote:
>
> Reading the code for a little bit, it looks like get_user_pages
> interprets both PROT_NONE and PAGE_NUMA ptes as present, and will
> simply return the page to the caller.
So the thing is, I don't think the code should even get that far.
It should just fail in check_vma_flags() (possibly after doing the
fast-lookup of the page tables, but that would fail with PROT_NONE).
But thanks to FOLL_FORCE, it doesn't. So things that actually use the
page array and prot_none can get access to the underlying data.
Linus
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2016-09-26 1:05 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-11 22:54 Lorenzo Stoakes
2016-09-11 22:59 ` Lorenzo Stoakes
2016-09-25 18:47 ` Lorenzo Stoakes
2016-09-25 20:52 ` Linus Torvalds
2016-09-25 22:24 ` Linus Torvalds
2016-09-25 22:34 ` Rik van Riel
2016-09-25 22:50 ` Linus Torvalds
2016-09-25 23:28 ` Hugh Dickins
2016-09-26 0:49 ` Rik van Riel
2016-09-26 1:05 ` Linus Torvalds [this message]
2016-10-07 10:07 ` Lorenzo Stoakes
2016-10-07 15:34 ` Linus Torvalds
2016-10-07 16:22 ` Lorenzo Stoakes
2016-10-07 18:16 ` Hugh Dickins
2016-10-07 18:26 ` Lorenzo Stoakes
2016-10-10 7:47 ` Jan Kara
2016-10-10 8:28 ` Lorenzo Stoakes
2016-10-10 16:37 ` Jan Kara
2016-09-26 8:19 ` Mel Gorman
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=CA+55aFyP2Aw7ET5oNX9fB644PGKrguk-mhXdcEN_aHvnVVsUjg@mail.gmail.com \
--to=torvalds@linux-foundation.org \
--cc=akpm@linux-foundation.org \
--cc=hughd@google.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=lstoakes@gmail.com \
--cc=mgorman@techsingularity.net \
--cc=riel@redhat.com \
--cc=robert@ocallahan.org \
--cc=tbsaunde@tbsaunde.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