netdev - Re: [RFC][PATCHES] iov

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20141208192816.GH22149@ZenIV.linux.org.uk>
Date:	Mon, 8 Dec 2014 19:28:17 +0000
From:	Al Viro <viro@...IV.linux.org.uk>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	"Kirill A. Shutemov" <kirill@...temov.name>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	linux-fsdevel <linux-fsdevel@...r.kernel.org>,
	Network Development <netdev@...r.kernel.org>
Subject: Re: [RFC][PATCHES] iov_iter.c rewrite

On Mon, Dec 08, 2014 at 10:57:31AM -0800, Linus Torvalds wrote:
> So the whole "get_page()" thing is broken. Iterating over pages in a
> KVEC is simply wrong, wrong, wrong. It needs to fail.

Well, _that_ is easy to do, of course...  E.g. by replacing that thing in
iov_iter_get_pages()/iov_iter_get_pages_alloc() with ({ return -EFAULT; })
will do it.

> Iterating over a KVEC to *copy* data is ok. But no page lookup stuff
> or page reference things.
> 
> The old code that apparently used "get_user_pages_fast()" was ok
> almost by mistake, because it fails on all kernel pages.

On x86 it does, but I don't see anything obvious in generic version in
mm/gup.c, so the old code might still have a problem on some architectures.
What am I missing here?
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html