[irqchip: irq/irqchip-next] irqchip/stm32-exti: Prevent illegal read due to unbounded DT value

[irqchip-bot for Antonio Borneo]

The following commit has been merged into the irq/irqchip-next branch of irqchip:

Commit-ID:     c16ae609214e835692c33b1a090b5a15bf1b9e7e
Gitweb:        https://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms/c16ae609214e835692c33b1a090b5a15bf1b9e7e
Author:        Antonio Borneo <antonio.borneo@xxxxxxxxxxx>
AuthorDate:    Mon, 06 Jun 2022 18:27:54 +02:00
Committer:     Marc Zyngier <maz@xxxxxxxxxx>
CommitterDate: Thu, 07 Jul 2022 09:07:44 +01:00

irqchip/stm32-exti: Prevent illegal read due to unbounded DT value

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@xxxxxxxxxxx>
Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20220606162757.415354-4-antonio.borneo@xxxxxxxxxxx
---
 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 1145f06..e2722e4 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];