linux-kernel - [PATCH v4.1 4/4] locking/lockdep: Add kasan_check_byte() check in lock

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Message-ID: <20250214195242.2480920-1-longman@redhat.com>
Date: Fri, 14 Feb 2025 14:52:42 -0500
From: Waiman Long <longman@...hat.com>
To: Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>,
	Will Deacon <will.deacon@....com>,
	Boqun Feng <boqun.feng@...il.com>,
	Andrey Ryabinin <ryabinin.a.a@...il.com>,
	Alexander Potapenko <glider@...gle.com>,
	Andrey Konovalov <andreyknvl@...il.com>,
	Dmitry Vyukov <dvyukov@...gle.com>,
	Vincenzo Frascino <vincenzo.frascino@....com>,
	Marco Elver <elver@...gle.com>
Cc: linux-kernel@...r.kernel.org,
	kasan-dev@...glegroups.com,
	Waiman Long <longman@...hat.com>
Subject: [PATCH v4.1 4/4] locking/lockdep: Add kasan_check_byte() check in lock_acquire()

KASAN instrumentation of lockdep has been disabled as we don't need
KASAN to check the validity of lockdep internal data structures and
incur unnecessary performance overhead. However, the lockdep_map pointer
passed in externally may not be valid (e.g. use-after-free) and we run
the risk of using garbage data resulting in false lockdep reports.

Add kasan_check_byte() call in lock_acquire() for non kernel core data
object to catch invalid lockdep_map and print out a KASAN report before
any lockdep splat, if any.

Suggested-by: Marco Elver <elver@...gle.com>
Signed-off-by: Waiman Long <longman@...hat.com>
---
 kernel/locking/lockdep.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 8436f017c74d..b15757e63626 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -57,6 +57,7 @@
 #include <linux/lockdep.h>
 #include <linux/context_tracking.h>
 #include <linux/console.h>
+#include <linux/kasan.h>
 
 #include <asm/sections.h>
 
@@ -5830,6 +5831,14 @@ void lock_acquire(struct lockdep_map *lock, unsigned int subclass,
 	if (!debug_locks)
 		return;
 
+	/*
+	 * As KASAN instrumentation is disabled and lock_acquire() is usually
+	 * the first lockdep call when a task tries to acquire a lock, add
+	 * kasan_check_byte() here to check for use-after-free and other
+	 * memory errors.
+	 */
+	kasan_check_byte(lock);
+
 	if (unlikely(!lockdep_enabled())) {
 		/* XXX allow trylock from NMI ?!? */
 		if (lockdep_nmi() && !trylock) {
-- 
2.48.1