[tip:irq/core] genirq: Robustify handle_percpu_devid_irq()

[tip-bot for Thomas Gleixner <tipbot@zytor.com>]

Commit-ID:  fc590c22f9f056ab50190b797f6cacead29f9b75
Gitweb:     http://git.kernel.org/tip/fc590c22f9f056ab50190b797f6cacead29f9b75
Author:     Thomas Gleixner <tglx@linutronix.de>
AuthorDate: Fri, 2 Sep 2016 14:45:19 +0200
Committer:  Thomas Gleixner <tglx@linutronix.de>
CommitDate: Fri, 2 Sep 2016 18:06:49 +0200

genirq: Robustify handle_percpu_devid_irq()

The percpu_devid handler is not robust against spurious interrupts. If a
spurious interrupt happens and no action is installed then the handler
crashes with a NULL pointer dereference.

Add a sanity check for this and log the wreckage once in dmesg.

Reported-by: Majun <majun258@huawei.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: guohanjun@huawei.com
Cc: dingtianhong@huawei.com
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lkml.kernel.org/r/alpine.DEB.2.20.1609021436160.5647@nanos

---
 kernel/irq/chip.c | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c
index b4c1bc7..93c373a 100644
--- a/kernel/irq/chip.c
+++ b/kernel/irq/chip.c
@@ -756,7 +756,6 @@ void handle_percpu_devid_irq(struct irq_desc *desc)
 {
 	struct irq_chip *chip = irq_desc_get_chip(desc);
 	struct irqaction *action = desc->action;
-	void *dev_id = raw_cpu_ptr(action->percpu_dev_id);
 	unsigned int irq = irq_desc_get_irq(desc);
 	irqreturn_t res;
 
@@ -765,9 +764,20 @@ void handle_percpu_devid_irq(struct irq_desc *desc)
 	if (chip->irq_ack)
 		chip->irq_ack(&desc->irq_data);
 
-	trace_irq_handler_entry(irq, action);
-	res = action->handler(irq, dev_id);
-	trace_irq_handler_exit(irq, action, res);
+	if (likely(action)) {
+		trace_irq_handler_entry(irq, action);
+		res = action->handler(irq, raw_cpu_ptr(action->percpu_dev_id));
+		trace_irq_handler_exit(irq, action, res);
+	} else {
+		unsigned int cpu = smp_processor_id();
+		bool enabled = cpumask_test_cpu(cpu, desc->percpu_enabled);
+
+		if (enabled)
+			irq_percpu_disable(desc, cpu);
+
+		pr_err_once("Spurious%s percpu IRQ%u on CPU%u\n",
+			    enabled ? " and unmasked" : "", irq, cpu);
+	}
 
 	if (chip->irq_eoi)
 		chip->irq_eoi(&desc->irq_data);