Merge tag 'timers-urgent-2020-04-05' of git://git.kernel.org/pub/scm/…

…linux/kernel/git/tip/tip

Pull timer fixes from Thomas Gleixner:
 "Two timer subsystem fixes:

   - Prevent a use after free in the new lockdep state tracking for
     hrtimers

   - Add missing parenthesis in the VF pit timer driver"

* tag 'timers-urgent-2020-04-05' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  clocksource/drivers/timer-vf-pit: Add missing parenthesis
  hrtimer: Don't dereference the hrtimer pointer after the callback

drivers/clocksource/timer-vf-pit.c

@@ -129,7 +129,7 @@ static int __init pit_clockevent_init(unsigned long rate, int irq)
 	__raw_writel(PITTFLG_TIF, clkevt_base + PITTFLG);
 
 	BUG_ON(request_irq(irq, pit_timer_interrupt, IRQF_TIMER | IRQF_IRQPOLL,
-			   "VF pit timer", &clockevent_pit);
+			   "VF pit timer", &clockevent_pit));
 
 	clockevent_pit.cpumask = cpumask_of(0);
 	clockevent_pit.irq = irq;

include/linux/irqflags.h

@@ -58,16 +58,21 @@ do {						\
 } while (0)
 
 # define lockdep_hrtimer_enter(__hrtimer)		\
-	  do {						\
-		  if (!__hrtimer->is_hard)		\
-			current->irq_config = 1;	\
-	  } while (0)
-
-# define lockdep_hrtimer_exit(__hrtimer)		\
-	  do {						\
-		  if (!__hrtimer->is_hard)		\
+({							\
+	bool __expires_hardirq = true;			\
+							\
+	if (!__hrtimer->is_hard) {			\
+		current->irq_config = 1;		\
+		__expires_hardirq = false;		\
+	}						\
+	__expires_hardirq;				\
+})
+
+# define lockdep_hrtimer_exit(__expires_hardirq)	\
+	do {						\
+		if (!__expires_hardirq)			\
 			current->irq_config = 0;	\
-	  } while (0)
+	} while (0)
 
 # define lockdep_posixtimer_enter()				\
 	  do {							\
@@ -102,8 +107,8 @@ do {						\
 # define lockdep_hardirq_exit()		do { } while (0)
 # define lockdep_softirq_enter()	do { } while (0)
 # define lockdep_softirq_exit()		do { } while (0)
-# define lockdep_hrtimer_enter(__hrtimer)		do { } while (0)
-# define lockdep_hrtimer_exit(__hrtimer)		do { } while (0)
+# define lockdep_hrtimer_enter(__hrtimer)	false
+# define lockdep_hrtimer_exit(__context)	do { } while (0)
 # define lockdep_posixtimer_enter()		do { } while (0)
 # define lockdep_posixtimer_exit()		do { } while (0)
 # define lockdep_irq_work_enter(__work)		do { } while (0)

kernel/time/hrtimer.c

@@ -1480,6 +1480,7 @@ static void __run_hrtimer(struct hrtimer_cpu_base *cpu_base,
 			  unsigned long flags) __must_hold(&cpu_base->lock)
 {
 	enum hrtimer_restart (*fn)(struct hrtimer *);
+	bool expires_in_hardirq;
 	int restart;
 
 	lockdep_assert_held(&cpu_base->lock);
@@ -1514,11 +1515,11 @@ static void __run_hrtimer(struct hrtimer_cpu_base *cpu_base,
 	 */
 	raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
 	trace_hrtimer_expire_entry(timer, now);
-	lockdep_hrtimer_enter(timer);
+	expires_in_hardirq = lockdep_hrtimer_enter(timer);
 
 	restart = fn(timer);
 
-	lockdep_hrtimer_exit(timer);
+	lockdep_hrtimer_exit(expires_in_hardirq);
 	trace_hrtimer_expire_exit(timer);
 	raw_spin_lock_irq(&cpu_base->lock);