[PATCH v2 3/6] irqchip/stm32-exti: Prevent illegal read due to unbounded DT value

[Antonio Borneo]

The value hwirq is received from DT. If it exceeds the maximum
valid value it causes the code to address unexisting irq chips
reading outside the array boundary.

Check the value of hwirq before using it.

Signed-off-by: Antonio Borneo <antonio.borneo at foss.st.com>
---
 drivers/irqchip/irq-stm32-exti.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/irqchip/irq-stm32-exti.c b/drivers/irqchip/irq-stm32-exti.c
index 1145f064faa8..e2722e499ae5 100644
--- a/drivers/irqchip/irq-stm32-exti.c
+++ b/drivers/irqchip/irq-stm32-exti.c
@@ -713,6 +713,9 @@ static int stm32_exti_h_domain_alloc(struct irq_domain *dm,
 	int bank;
 
 	hwirq = fwspec->param[0];
+	if (hwirq >= host_data->drv_data->bank_nr * IRQS_PER_BANK)
+		return -EINVAL;
+
 	bank  = hwirq / IRQS_PER_BANK;
 	chip_data = &host_data->chips_data[bank];
 
-- 
2.36.1