[ 094/117] gpio: mpc8xxx: Prevent NULL pointer deref in demux handler

[Ben Hutchings]

3.2-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Thomas Gleixner <tglx@xxxxxxxxxxxxx>

commit d6de85e85edcc38c9edcde45a0a568818fcddc13 upstream.

commit cfadd838(powerpc/8xxx: Fix interrupt handling in MPC8xxx GPIO
driver) added an unconditional call of chip->irq_eoi() to the demux
handler.

This leads to a NULL pointer derefernce on MPC512x platforms which use
this driver as well.

Make it conditional.

Reported-by: Thomas Wucher <thwucher@xxxxxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Felix Radensky <felix@xxxxxxxxxxxxxxxx>
Cc: Kumar Gala <galak@xxxxxxxxxxxxxxxxxxx>
Cc: Grant Likely <grant.likely@xxxxxxxxxxxx>
Signed-off-by: Grant Likely <grant.likely@xxxxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 drivers/gpio/gpio-mpc8xxx.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpio/gpio-mpc8xxx.c b/drivers/gpio/gpio-mpc8xxx.c
index e6568c1..5a1817e 100644
--- a/drivers/gpio/gpio-mpc8xxx.c
+++ b/drivers/gpio/gpio-mpc8xxx.c
@@ -163,7 +163,8 @@ static void mpc8xxx_gpio_irq_cascade(unsigned int irq, struct irq_desc *desc)
 	if (mask)
 		generic_handle_irq(irq_linear_revmap(mpc8xxx_gc->irq,
 						     32 - ffs(mask)));
-	chip->irq_eoi(&desc->irq_data);
+	if (chip->irq_eoi)
+		chip->irq_eoi(&desc->irq_data);
 }
 
 static void mpc8xxx_irq_unmask(struct irq_data *d)


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