From mboxrd@z Thu Jan  1 00:00:00 1970
From: Christoph Hellwig <hch@infradead.org>
Subject: Re: [kernel-hardening] Re: [PATCH v9 1/4] syscalls: Verify address
 limit before returning to user-mode
Date: Wed, 10 May 2017 00:15:11 -0700
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To: Kees Cook <keescook@chromium.org>
Cc: Mark Rutland <mark.rutland@arm.com>, Brian Gerst <brgerst@gmail.com>, Kernel Hardening <kernel-hardening@lists.openwall.com>, Catalin Marinas <catalin.marinas@arm.com>, Heiko Carstens <heiko.carstens@de.ibm.com>, Oleg Nesterov <oleg@redhat.com>, David Howells <dhowells@redhat.com>, Dave Hansen <dave.hansen@intel.com>, "H . Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@kernel.org>, Pavel Tikhomirov <ptikhomirov@virtuozzo.com>, linux-s390 <linux-s390@vger.kernel.org>, the arch/x86 maintainers <x86@kernel.org>, Russell King <linux@armlinux.org.uk>, Christoph Hellwig <hch@infradead.org>, Christian Borntraeger <borntraeger@de.ibm.com>, =?iso-8859-1?Q?Ren=E9?= Nyffenegger <mail@renenyffenegger.ch>, Greg KH <greg@kroah.com>, "Paul E . McKenney" <paulmck@linux.vnet.ibm.com>, Rik van Riel <riel@redhat.com>, Peter Zijlstra <a.p.zijlstra@chello.nl>, Arnd Bergmann <arnd@arndb.de>
List-Id: linux-api@vger.kernel.org

On Tue, May 09, 2017 at 04:31:00PM -0700, Kees Cook wrote:
> > I don't like silent fixups.  If we want to do this, we should BUG or
> > at least WARN, not just change the addr limit.  But I'm also not
> > convinced it's indicative of an actual bug here.
> 
> Nothing should enter that function with KERNEL_DS set, right?

It might very well do.  Various drivers or the networking code mess
with the address limits for fairly broad sections of code.