linux-kernel - [PATCH] irqchip/gic: prevent buffer overflow in gic_ipi_send

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Message-ID: <048ff3bb-09d1-2e60-4f3b-611e2bfde7aa@omp.ru>
Date: Wed, 4 Sep 2024 23:23:32 +0300
From: Sergey Shtylyov <s.shtylyov@....ru>
To: Thomas Gleixner <tglx@...utronix.de>, <linux-kernel@...r.kernel.org>, Marc
 Zyngier <maz@...nel.org>, <linux-arm-kernel@...ts.infradead.org>
Subject: [PATCH] irqchip/gic: prevent buffer overflow in gic_ipi_send_mask()

ARM GIC arch v2 spec claims support for just 8 CPU interfaces.  However,
looking at the GIC driver's irq_set_affinity() method, it seems that the
passed CPU mask may contain the logical CPU #s beyond 8, and that method
filters them out before reading gic_cpu_map[], bailing out with -EINVAL.
Such check should also be performed in the ipi_send_mask() method where
it uses for_each_cpu(), in order to prevent accessing beyond the end of
gic_cpu_map[] there as well...

Found by Linux Verification Center (linuxtesting.org) with the Svace static
analysis tool.

Fixes: 384a290283fd ("ARM: gic: use a private mapping for CPU target interfaces")
Signed-off-by: Sergey Shtylyov <s.shtylyov@....ru>

---
The patch is against the irq/core branch of the tip.git repo...

 drivers/irqchip/irq-gic.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

Index: tip/drivers/irqchip/irq-gic.c
===================================================================
--- tip.orig/drivers/irqchip/irq-gic.c
+++ tip/drivers/irqchip/irq-gic.c
@@ -832,8 +832,11 @@ static void gic_ipi_send_mask(struct irq
 	gic_lock_irqsave(flags);

 	/* Convert our logical CPU mask into a physical one. */
-	for_each_cpu(cpu, mask)
+	for_each_cpu(cpu, mask) {
+		if (cpu >= NR_GIC_CPU_IF)
+			break;
 		map |= gic_cpu_map[cpu];
+	}

 	/*
 	 * Ensure that stores to Normal memory are visible to the