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Date: Fri, 12 May 2017 00:35:21 -0700
From: Christoph Hellwig <hch@infradead.org>
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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/>
List-Post: <mailto:kernel-hardening@lists.openwall.com>
To: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Ingo Molnar <mingo@kernel.org>, Andy Lutomirski <luto@kernel.org>, Christoph Hellwig <hch@infradead.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 Fri, May 12, 2017 at 08:15:49AM +0100, Al Viro wrote:
> And converting everything to ->read_iter()/->write_iter() means an insane
> amount of code churn, not to mention coping with random bogosities in
> semantics.  ->read() and ->write() are going to stay around, pretty
> much indefinitely.

But I don't think kernel users of them have to.  I've been digging
through the calllers and will send an analysis to the list in a bit.