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Message-Id: <20160822175307.GI3482@linux.vnet.ibm.com>
Date: Mon, 22 Aug 2016 10:53:07 -0700
From: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To: Arnd Bergmann <arnd@...db.de>
Cc: Kees Cook <keescook@...omium.org>, Laura Abbott <labbott@...hat.com>,
Steven Rostedt <rostedt@...dmis.org>,
Daniel Micay <danielmicay@...il.com>, Joe Perches <joe@...ches.com>,
Stephen Boyd <sboyd@...eaurora.org>,
Syed Rameez Mustafa <rameezmustafa@...eaurora.org>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Josh Triplett <josh@...htriplett.org>,
Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
Lai Jiangshan <jiangshanlai@...il.com>,
"Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>,
"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
Michael Ellerman <mpe@...erman.id.au>,
Andrew Morton <akpm@...ux-foundation.org>,
Dan Williams <dan.j.williams@...el.com>, Jan Kara <jack@...e.cz>,
Thomas Gleixner <tglx@...utronix.de>, Josef Bacik <jbacik@...com>,
Ingo Molnar <mingo@...nel.org>, Tejun Heo <tj@...nel.org>,
Andrey Ryabinin <aryabinin@...tuozzo.com>,
Nikolay Aleksandrov <nikolay@...ulusnetworks.com>,
Dmitry Vyukov <dvyukov@...gle.com>, linux-kernel@...r.kernel.org,
kernel-hardening@...ts.openwall.com
Subject: Re: [PATCH v3 4/5] bug: Provide toggle for BUG on data corruption
On Mon, Aug 22, 2016 at 03:15:35PM +0200, Arnd Bergmann wrote:
> On Wednesday, August 17, 2016 2:42:11 PM CEST Kees Cook wrote:
> > +
> > +/*
> > + * Since detected data corruption should stop operation on the affected
> > + * structures, this returns false if the corruption condition is found.
> > + */
> > +#define CHECK_DATA_CORRUPTION(condition, fmt, ...) \
> > + do { \
> > + if (unlikely(condition)) { \
> > + if (IS_ENABLED(CONFIG_BUG_ON_DATA_CORRUPTION)) { \
> > + pr_err(fmt, ##__VA_ARGS__); \
> > + BUG(); \
> > + } else \
> > + WARN(1, fmt, ##__VA_ARGS__); \
> > + return false; \
> > + } \
> > + } while (0)
> > +
>
> I think the "return false" inside of the macro makes it easy to misread
> what is actually going on.
>
> How about making it a macro that returns the condition argument?
>
> #define CHECK_DATA_CORRUPTION(condition, fmt, ...) \
> ({ \
> bool _condition = unlikely(condition); \
> if (_condition) { \
> ...
> } \
> _condition; \
> })
That does look better, now that you mention it. Kees, any objections?
Thanx, Paul
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