From: Andrea Arcangeli <aarcange@redhat.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Hillf Danton <dhillf@gmail.com>,
LKML <linux-kernel@vger.kernel.org>,
linux-mm@kvack.org
Subject: Re: [PATCH] mm/huge_memory: Clean up typo when copying user highpage
Date: Thu, 13 Oct 2011 00:24:54 +0200 [thread overview]
Message-ID: <20111012222454.GA3218@redhat.com> (raw)
In-Reply-To: <20111012134224.786191ac.akpm@linux-foundation.org>
On Wed, Oct 12, 2011 at 01:42:24PM -0700, Andrew Morton wrote:
> On Wed, 12 Oct 2011 19:51:48 +0200
> Andrea Arcangeli <aarcange@redhat.com> wrote:
>
> > On Wed, Oct 12, 2011 at 10:39:36PM +0800, Hillf Danton wrote:
> > > Hi Andrea
> > >
> > > When copying user highpage, the PAGE_SHIFT in the third parameter is a typo,
> > > I think, and is replaced with PAGE_SIZE.
> >
> > That looks correct. I wonder how it was not noticed yet. Because it
> > can't go out of bound, it didn't risk to crash the kernel and it didn't
> > not risk to expose random data to the cowing task. So it shouldn't
> > have security implications as far as I can tell, but the app could
> > malfunction and crash (userland corruption only).
>
> Which architectures care about the copy_user_page() `vaddr' argument?
> mips, perhaps? I suspect the intersection between those architectures
> and archs-which-implement-hugepages is the empty set.
Yes it's not happening. debug_cow was specifically meant to trap this
very case so there was little chance it could go unnoticed.
Never mind.... still the patch is correct and good idea to apply as cleanup.
--
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/ .
Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
prev parent reply other threads:[~2011-10-12 22:24 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-10-12 14:39 [PATCH] mm/huge_memory: Clean up typo when copying user highpage Hillf Danton
2011-10-12 15:56 ` Johannes Weiner
2011-10-12 17:51 ` Andrea Arcangeli
2011-10-12 20:42 ` Andrew Morton
2011-10-12 22:24 ` Andrea Arcangeli [this message]
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=20111012222454.GA3218@redhat.com \
--to=aarcange@redhat.com \
--cc=akpm@linux-foundation.org \
--cc=dhillf@gmail.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.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).