kernel-hardening - [PATCH v3 0/5] bug: Provide toggle for BUG on data corruption

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Date: Wed, 17 Aug 2016 14:42:07 -0700
From: Kees Cook <keescook@...omium.org>
To: "Paul E . McKenney" <paulmck@...ux.vnet.ibm.com>
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>,
	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>,
	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: [PATCH v3 0/5] bug: Provide toggle for BUG on data corruption

This adds CONFIG_BUG_ON_DATA_CORRUPTION to trigger BUG()s when the kernel
encounters unexpected data structure integrity as currently detected
with CONFIG_DEBUG_LIST.

Specifically list operations have been a target for widening flaws to gain
"write anywhere" primitives for attackers, so this also consolidates the
debug checking to avoid code and check duplication (e.g. RCU list debug
was missing a check that got added to regular list debug). It also stops
manipulations when corruption is detected, since worsening the corruption
makes no sense. (Really, everyone should build with CONFIG_DEBUG_LIST
since the checks are so inexpensive.)

This is mostly a refactoring of similar code from PaX and Grsecurity,
along with MSM kernel changes by Syed Rameez Mustafa.

Along with the patches is a new lkdtm test to validate that setting
CONFIG_DEBUG_LIST actually does what is desired.

Thanks,

-Kees

v3:
- fix MSM attribution, sboyd
- use pr_err, joe

v2:
- consolidate printk/WARN/BUG/return logic into a CONFIG-specific macro
- drop non-list BUGs, labbott

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