linux-kernel - [PATCH] genirq:Dereference desc after null pointer check

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Date:   Tue, 17 Jul 2018 04:33:09 +0530
From:   RAGHU Halharvi <raghuhack78@...il.com>
To:     linux-kernel@...r.kernel.org
Cc:     RAGHU Halharvi <raghuhack78@...il.com>, tglx@...utronix.de
Subject: [PATCH] genirq:Dereference desc after null pointer check

* Remove unchecked dereferencing of *desc & assigning it local irq
	variable
* Move the assignement after proper check of *desc for NULL pointer.

Signed-off-by: RAGHU Halharvi <raghuhack78@...il.com>
---
 kernel/irq/manage.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index facfecfc543c..33c77eb4fdb6 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -1557,15 +1557,16 @@ EXPORT_SYMBOL_GPL(setup_irq);
  */
 static struct irqaction *__free_irq(struct irq_desc *desc, void *dev_id)
 {
-	unsigned irq = desc->irq_data.irq;
+	unsigned int irq;
 	struct irqaction *action, **action_ptr;
 	unsigned long flags;
 
-	WARN(in_interrupt(), "Trying to free IRQ %d from IRQ context!\n", irq);
 
 	if (!desc)
 		return NULL;
 
+	irq = desc->irq_data.irq;
+	WARN(in_interrupt(), "Trying to free IRQ %d from IRQ context!\n", irq);
 	mutex_lock(&desc->request_mutex);
 	chip_bus_lock(desc);
 	raw_spin_lock_irqsave(&desc->lock, flags);
-- 
2.17.1