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Date: Sat, 13 May 2017 00:21:37 -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: Peter Zijlstra <peterz@infradead.org>
Cc: Russell King - ARM Linux <linux@armlinux.org.uk>, Kees Cook <keescook@chromium.org>, Linus Torvalds <torvalds@linux-foundation.org>, Mark Rutland <mark.rutland@arm.com>, Kernel Hardening <kernel-hardening@lists.openwall.com>, Greg KH <greg@kroah.com>, Heiko Carstens <heiko.carstens@de.ibm.com>, LKML <linux-kernel@vger.kernel.org>, 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>, Will Deacon <will.deacon@arm.com>, Christian Borntraeger <borntraeger@de.ibm.com>, =?iso-8859-1?Q?Ren=E9?= Nyffenegger <mail@renenyffenegger.ch>, Catalin Marinas <catalin.marinas@arm.com>, "Paul E . McKenney" <paulmck@linux.vnet.ibm.com>, Rik van Riel <riel@redhat.com>, Arnd Bergmann <arnd@arndb.de>, Brian Gerst <brgerst@gmail.com>, Borislav Petkov <bp@alien8.de>, Al Viro <viro@zeniv.linux.org.uk>, Andy Lutomirski <luto@kernel.org>, Josh Poimboeuf <jpoimboe@redhat.com>, Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>, "linux-arm-kernel@lists.infradead.org" <linux-arm-kernel@lists.infradead.org>, Linux API <linux-api@vger.kernel.org>, Oleg Nesterov <oleg@redhat.com>, Daniel Micay <danielmicay@gmail.com>, James Morse <james.morse@arm.com>, "Eric W . Biederman" <ebiederm@xmission.com>, Martin Schwidefsky <schwidefsky@de.ibm.com>, Paolo Bonzini <pbonzini@redhat.com>, Andrew Morton <akpm@linux-foundation.org>, Thomas Garnier <thgarnie@google.com>, "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
List-ID: <linux-s390.vger.kernel.org>

On Fri, May 12, 2017 at 10:30:44PM +0200, Peter Zijlstra wrote:
> On stack variable length arrays get implemented by the compiler doing
> alloca(), and we sadly have a few of those around.

I've just got rid of one of those and I wish they would appear
entirely as they are horrible in so many different ways.  Sparse
warns about them, btw.