linux-kernel - [PATCH v2 3/7] bug: Use WARN_ONCE() for CHECK_DATA

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Date:   Tue,  4 Apr 2017 15:12:14 -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 3/7] bug: Use WARN_ONCE() for CHECK_DATA_CORRUPTION()

Since users of CHECK_DATA_CORRUPTION() should be failing safe, the
condition that triggers a WARN() may recur. This would mean a logging
DoS of the system, so switch to WARN_ONCE() instead. (Those wanting
per-instance notifications should already be building with
CONFIG_BUG_ON_DATA_CORRUPTION so there is no change in that case.)

Signed-off-by: Kees Cook <keescook@...omium.org>
---
 include/linux/bug.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/bug.h b/include/linux/bug.h
index b6cfcb7f778f..c011438a7c6c 100644
--- a/include/linux/bug.h
+++ b/include/linux/bug.h
@@ -136,7 +136,7 @@ static inline __must_check bool check_data_corruption(bool v) { return v; }
 				pr_err(fmt, ##__VA_ARGS__);		 \
 				BUG();					 \
 			} else						 \
-				WARN(1, fmt, ##__VA_ARGS__);		 \
+				WARN_ONCE(1, fmt, ##__VA_ARGS__);	 \
 		}							 \
 		unlikely(corruption);					 \
 	}))
-- 
2.7.4