linux-kernel - [tip: timers/core] clocksource/drivers/exynos_mct: Handle DTS with higher number of interrupts

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Date:   Mon, 14 Mar 2022 09:28:28 -0000
From:   "tip-bot2 for Krzysztof Kozlowski" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>,
        Alim Akhtar <alim.akhtar@...sung.com>,
        Daniel Lezcano <daniel.lezcano@...aro.org>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [tip: timers/core] clocksource/drivers/exynos_mct: Handle DTS with
 higher number of interrupts

The following commit has been merged into the timers/core branch of tip:

Commit-ID:     ab8da93dc06d82f464c47ab30e6c75190702f369
Gitweb:        https://git.kernel.org/tip/ab8da93dc06d82f464c47ab30e6c75190702f369
Author:        Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>
AuthorDate:    Sun, 20 Feb 2022 11:38:15 +01:00
Committer:     Daniel Lezcano <daniel.lezcano@...aro.org>
CommitterDate: Mon, 07 Mar 2022 18:27:22 +01:00

clocksource/drivers/exynos_mct: Handle DTS with higher number of interrupts

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@...onical.com>
Reviewed-by: Alim Akhtar <alim.akhtar@...sung.com>
Link: https://lore.kernel.org/r/20220220103815.135380-1-krzysztof.kozlowski@canonical.com
Signed-off-by: Daniel Lezcano <daniel.lezcano@...aro.org>
---
 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 6db3d55..03782b3 100644
--- a/drivers/clocksource/exynos_mct.c
+++ b/drivers/clocksource/exynos_mct.c
@@ -541,6 +541,11 @@ 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);
 
@@ -553,11 +558,14 @@ 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,