[PATCH 5.10 158/599] clocksource/drivers/exynos_mct: Handle DTS with higher number of interrupts

[Greg Kroah-Hartman]

From: Krzysztof Kozlowski <krzysztof.kozlowski@xxxxxxxxxxxxx>

[ Upstream commit ab8da93dc06d82f464c47ab30e6c75190702f369 ]

The driver statically defines maximum number of interrupts it can
handle, however it does not respect that limit when configuring them.
When provided with a DTS with more interrupts than assumed, the driver
will overwrite static array mct_irqs leading to silent memory
corruption.

Validate the interrupts coming from DTS to avoid this.  This does not
change the fact that such DTS might not boot at all, because it is
simply incompatible, however at least some warning will be printed.

Fixes: 36ba5d527e95 ("ARM: EXYNOS: add device tree support for MCT controller driver")
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@xxxxxxxxxxxxx>
Reviewed-by: Alim Akhtar <alim.akhtar@xxxxxxxxxxx>
Link: https://lore.kernel.org/r/20220220103815.135380-1-krzysztof.kozlowski@xxxxxxxxxxxxx
Signed-off-by: Daniel Lezcano <daniel.lezcano@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/clocksource/exynos_mct.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/clocksource/exynos_mct.c b/drivers/clocksource/exynos_mct.c
index 5533c9afc088..df194b05e944 100644
--- a/drivers/clocksource/exynos_mct.c
+++ b/drivers/clocksource/exynos_mct.c
@@ -531,6 +531,11 @@ static int __init exynos4_timer_interrupts(struct device_node *np,
 	 * irqs are specified.
 	 */
 	nr_irqs = of_irq_count(np);
+	if (nr_irqs > ARRAY_SIZE(mct_irqs)) {
+		pr_err("exynos-mct: too many (%d) interrupts configured in DT\n",
+			nr_irqs);
+		nr_irqs = ARRAY_SIZE(mct_irqs);
+	}
 	for (i = MCT_L0_IRQ; i < nr_irqs; i++)
 		mct_irqs[i] = irq_of_parse_and_map(np, i);
 
@@ -543,11 +548,14 @@ static int __init exynos4_timer_interrupts(struct device_node *np,
 		     mct_irqs[MCT_L0_IRQ], err);
 	} else {
 		for_each_possible_cpu(cpu) {
-			int mct_irq = mct_irqs[MCT_L0_IRQ + cpu];
+			int mct_irq;
 			struct mct_clock_event_device *pcpu_mevt =
 				per_cpu_ptr(&percpu_mct_tick, cpu);
 
 			pcpu_mevt->evt.irq = -1;
+			if (MCT_L0_IRQ + cpu >= ARRAY_SIZE(mct_irqs))
+				break;
+			mct_irq = mct_irqs[MCT_L0_IRQ + cpu];
 
 			irq_set_status_flags(mct_irq, IRQ_NOAUTOEN);
 			if (request_irq(mct_irq,
-- 
2.34.1