linux-kernel - [PATCH 2/2] irqchip/mmp: Avoid overflowing icu

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Date:   Wed, 19 Feb 2020 09:00:24 +0100
From:   Lubomir Rintel <lkundrak@...sk>
To:     Marc Zyngier <maz@...nel.org>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Jason Cooper <jason@...edaemon.net>,
        linux-kernel@...r.kernel.org, Lubomir Rintel <lkundrak@...sk>
Subject: [PATCH 2/2] irqchip/mmp: Avoid overflowing icu_data[]

In case someone messes up and adds too many interrupt muxes in the device
tree, icu_data would overflow into things that follow it in bss, likely
mmp_icu2_base and mmp_icu_base.

Let's add a safeguard, so that we fail gracefully instead of panicking
at some later point for reasons that are then not immediately clear.

Signed-off-by: Lubomir Rintel <lkundrak@...sk>
---
 drivers/irqchip/irq-mmp.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/irqchip/irq-mmp.c b/drivers/irqchip/irq-mmp.c
index f597d96409a1f..c7ef2cea1c020 100644
--- a/drivers/irqchip/irq-mmp.c
+++ b/drivers/irqchip/irq-mmp.c
@@ -505,6 +505,11 @@ static int __init mmp2_mux_of_init(struct device_node *node,
 		return -ENODEV;
 
 	i = max_icu_nr;
+	if (i >= MAX_ICU_NR) {
+		pr_err("Too many interrupt muxes\n");
+		return -EINVAL;
+	}
+
 	ret = of_property_read_u32(node, "mrvl,intc-nr-irqs",
 				   &nr_irqs);
 	if (ret) {
-- 
2.24.1