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Date: Tue, 16 Aug 2016 17:26:09 -0700
From: Joe Perches <joe@...ches.com>
To: Kees Cook <keescook@...omium.org>, "Paul E . McKenney"
<paulmck@...ux.vnet.ibm.com>
Cc: Laura Abbott <labbott@...hat.com>, Steven Rostedt <rostedt@...dmis.org>,
Stephen Boyd <sboyd@...eaurora.org>, Daniel Micay <danielmicay@...il.com>,
Arnd Bergmann <arnd@...db.de>, 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>,
Dan Williams <dan.j.williams@...el.com>, Andrew Morton
<akpm@...ux-foundation.org>, Ingo Molnar <mingo@...nel.org>, Thomas
Gleixner <tglx@...utronix.de>, Josef Bacik <jbacik@...com>, Andrey Ryabinin
<aryabinin@...tuozzo.com>, Tejun Heo <tj@...nel.org>, Nikolay Aleksandrov
<nikolay@...ulusnetworks.com>, Dmitry Vyukov <dvyukov@...gle.com>,
linux-kernel@...r.kernel.org, kernel-hardening@...ts.openwall.com
Subject: Re: [PATCH v2 4/5] bug: Provide toggle for BUG on data corruption
On Tue, 2016-08-16 at 17:20 -0700, Kees Cook wrote:
> The kernel checks for cases of data structure corruption under some
> CONFIGs (e.g. CONFIG_DEBUG_LIST). When corruption is detected, some
> systems may want to BUG() immediately instead of letting the system run
> with known corruption. Usually these kinds of manipulation primitives can
> be used by security flaws to gain arbitrary memory write control. This
> provides a new config CONFIG_BUG_ON_DATA_CORRUPTION and a corresponding
> macro CHECK_DATA_CORRUPTION for handling these situations. Notably, even
> if not BUGing, the kernel should not continue processing the corrupted
> structure.
[]
> diff --git a/include/linux/bug.h b/include/linux/bug.h
[]
> @@ -118,4 +118,21 @@ static inline enum bug_trap_type report_bug(unsigned long bug_addr,
> }
>
> #endif /* CONFIG_GENERIC_BUG */
> +
> +/*
> + * 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, format...) \
My preference would be to use (condition, fmt, ...)
> + do { \
> + if (unlikely(condition)) { \
> + if (IS_ENABLED(CONFIG_BUG_ON_DATA_CORRUPTION)) { \
> + printk(KERN_ERR format); \
and
pr_err(fmt, ##__VA_ARGS__);
so that any use would also get any local pr_fmt applied as well.
> + BUG(); \
> + } else \
> + WARN(1, format); \
> + return false; \
> + } \
> + } while (0)
> +
> #endif /* _LINUX_BUG_H */
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