Commit 6c11c6e3 authored Jul 03, 2019 by Sebastian Andrzej Siewior Committed by Ingo Molnar Jul 25, 2019

locking/mutex: Test for initialized mutex



An uninitialized/ zeroed mutex will go unnoticed because there is no
check for it. There is a magic check in the unlock's slowpath path which
might go unnoticed if the unlock happens in the fastpath.

Add a ->magic check early in the mutex_lock() and mutex_trylock() path.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Will Deacon <will@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20190703092125.lsdf4gpsh2plhavb@linutronix.de


Signed-off-by: Ingo Molnar <mingo@kernel.org>

parent 30a35f79

kernel/locking/mutex.c

+10 −1

Original line number	Diff line number	Diff line
		@@ -908,6 +908,10 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass,

		might_sleep();

		#ifdef CONFIG_DEBUG_MUTEXES
		DEBUG_LOCKS_WARN_ON(lock->magic != lock);
		#endif

		ww = container_of(lock, struct ww_mutex, base);
		if (use_ww_ctx && ww_ctx) {
		if (unlikely(ww_ctx == READ_ONCE(ww->ctx)))
		@@ -1379,8 +1383,13 @@ __ww_mutex_lock_interruptible_slowpath(struct ww_mutex *lock,
		*/
		int __sched mutex_trylock(struct mutex *lock)
		{
		bool locked = __mutex_trylock(lock);
		bool locked;

		#ifdef CONFIG_DEBUG_MUTEXES
		DEBUG_LOCKS_WARN_ON(lock->magic != lock);
		#endif

		locked = __mutex_trylock(lock);
		if (locked)
		mutex_acquire(&lock->dep_map, 0, 1, _RET_IP_);

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