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Date: Wed, 10 May 2017 03:11:18 +0100
From: Al Viro <viro@ZenIV.linux.org.uk>
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Sender: Al Viro <viro@ftp.linux.org.uk>
Subject: Re: [kernel-hardening] Re: [PATCH v9 1/4] syscalls: Verify address
 limit before returning to user-mode
List-Archive: <https://lore.kernel.org/kernel-hardening/>
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To: Christoph Hellwig <hch@infradead.org>
Cc: Andy Lutomirski <luto@kernel.org>, Ingo Molnar <mingo@kernel.org>, Greg KH <greg@kroah.com>, Thomas Garnier <thgarnie@google.com>, Martin Schwidefsky <schwidefsky@de.ibm.com>, Heiko Carstens <heiko.carstens@de.ibm.com>, Dave Hansen <dave.hansen@intel.com>, Arnd Bergmann <arnd@arndb.de>, Thomas Gleixner <tglx@linutronix.de>, David Howells <dhowells@redhat.com>, =?iso-8859-1?Q?Ren=E9?= Nyffenegger <mail@renenyffenegger.ch>, Andrew Morton <akpm@linux-foundation.org>, "Paul E . McKenney" <paulmck@linux.vnet.ibm.com>, "Eric W . Biederman" <ebiederm@xmission.com>, Oleg Nesterov <oleg@redhat.com>, Pavel Tikhomirov <ptikhomirov@virtuozzo.com>, Ingo Molnar <mingo@redhat.com>, "H . Peter Anvin" <hpa@zytor.com>, Paolo Bonzini <pbonzini@redhat.com>, Rik van Riel <riel@redhat.com>, Kees Cook <keescook@chromium.org>, Josh Poimboeuf <jpoimboe@redhat.com>, Borislav Petkov <bp@alien8.de>, Brian Gerst <brgerst@gmail.com>, "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>, Christian Borntraeger <borntraeger@de.ibm.com>, Russell King <linux@armlinux.org.uk>, Will Deacon <will.deacon@arm.com>, Catalin Marinas <catalin.marinas@arm.com>, Mark Rutland <mark.rutland@arm.com>, James Morse <james.morse@arm.com>, linux-s390 <linux-s390@vger.kernel.org>, LKML <linux-kernel@vger.kernel.org>, Linux API <linux-api@vger.kernel.org>, the arch/x86 maintainers <x86@kernel.org>, "linux-arm-kernel@lists.infradead.org" <linux-arm-kernel@lists.infradead.org>, Kernel Hardening <kernel-hardening@lists.openwall.com>, Linus Torvalds <torvalds@linux-foundation.org>, Peter Zijlstra <a.p.zijlstra@chello.nl>
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On Tue, May 09, 2017 at 09:03:22AM -0700, Christoph Hellwig wrote:
> On Tue, May 09, 2017 at 06:02:50AM -0700, Christoph Hellwig wrote:
> > On Tue, May 09, 2017 at 06:00:01AM -0700, Andy Lutomirski wrote:
> > > fs/splice.c has some, ahem, interesting uses that have been the source
> > > of nasty exploits in the past.  Converting them to use iov_iter
> > > properly would be really, really nice.  Christoph, I don't suppose
> > > you'd like to do that?
> > 
> > I can take care of all the fs code including this one.

Oh?

> I spent the afternoon hacking up where I'd like this to head.  It's
> completely untested as of now:
> 
> 	http://git.infradead.org/users/hch/vfs.git/shortlog/refs/heads/setfs-elimination

And just what happens to driver that has no ->read_iter()?  Unless I'm
seriously misreading that, NAK with extreme prejudice.