linux-kernel - [PATCH v2 1/7] bug: Clarify help text for BUG_ON_DATA

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Date:   Tue,  4 Apr 2017 15:12:12 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Ingo Molnar <mingo@...nel.org>
Cc:     Kees Cook <keescook@...omium.org>,
        Peter Zijlstra <peterz@...radead.org>,
        "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
        Kalle Valo <kvalo@...eaurora.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Rik van Riel <riel@...hat.com>,
        Jakub Kicinski <jakub.kicinski@...ronome.com>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Olof Johansson <olof@...om.net>,
        Chris Wilson <chris@...is-wilson.co.uk>,
        George Spelvin <linux@...encehorizons.net>,
        Thomas Gleixner <tglx@...utronix.de>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        David Windsor <dwindsor@...il.com>,
        linux-kernel@...r.kernel.org, kernel-hardening@...ts.openwall.com
Subject: [PATCH v2 1/7] bug: Clarify help text for BUG_ON_DATA_CORRUPTION

This expands on the Kconfig help text for CONFIG_BUG_ON_DATA_CORRUPTION to
more clearly explain the rationale of BUG vs WARN. Additionally fixes a
grammar glitch in the macro comment.

Signed-off-by: Kees Cook <keescook@...omium.org>
---
 include/linux/bug.h | 3 ++-
 lib/Kconfig.debug   | 9 ++++++---
 2 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/include/linux/bug.h b/include/linux/bug.h
index 687b557fc5eb..db1e41c69bac 100644
--- a/include/linux/bug.h
+++ b/include/linux/bug.h
@@ -124,7 +124,8 @@ static inline enum bug_trap_type report_bug(unsigned long bug_addr,
 
 /*
  * Since detected data corruption should stop operation on the affected
- * structures. Return value must be checked and sanely acted on by caller.
+ * structures, require that the condition is checked and sanely acted on
+ * by the caller.
  */
 static inline __must_check bool check_data_corruption(bool v) { return v; }
 #define CHECK_DATA_CORRUPTION(condition, fmt, ...)			 \
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 77fadface4f9..5ac4d1148385 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -1998,9 +1998,12 @@ config BUG_ON_DATA_CORRUPTION
 	bool "Trigger a BUG when data corruption is detected"
 	select DEBUG_LIST
 	help
-	  Select this option if the kernel should BUG when it encounters
-	  data corruption in kernel memory structures when they get checked
-	  for validity.
+	  This option enables several inexpensive data corruption checks.
+	  Most of these checks normally just WARN and try to further avoid
+	  the corruption. Selecting this option upgrades these to BUGs so
+	  that the offending process is killed. Additionally, the system
+	  owner can furhter configure the system for immediate reboots
+	  (via panic_on_oops sysctl) or crash dumps.
 
 	  If unsure, say N.
 
-- 
2.7.4