linux-kernel - [PATCH v4 1/5] arch_topology: validate input frequencies to arch_set_freq

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Message-Id: <20200828173303.11939-2-ionela.voinescu@arm.com>
Date:   Fri, 28 Aug 2020 18:32:59 +0100
From:   Ionela Voinescu <ionela.voinescu@....com>
To:     rjw@...ysocki.net, viresh.kumar@...aro.org,
        dietmar.eggemann@....com, catalin.marinas@....com,
        sudeep.holla@....com, will@...nel.org, valentin.schneider@....com
Cc:     linux-pm@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, ionela.voinescu@....com
Subject: [PATCH v4 1/5] arch_topology: validate input frequencies to arch_set_freq_scale()

The current frequency passed to arch_set_freq_scale() could end up
being 0, signaling an error in setting a new frequency. Also, if the
maximum frequency in 0, this will result in a division by 0 error.

Therefore, validate these input values before using them for the
setting of the frequency scale factor.

Signed-off-by: Ionela Voinescu <ionela.voinescu@....com>
Cc: Sudeep Holla <sudeep.holla@....com>
Cc: Rafael J. Wysocki <rjw@...ysocki.net>
---
 drivers/base/arch_topology.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/base/arch_topology.c b/drivers/base/arch_topology.c
index 75f72d684294..5708eb724790 100644
--- a/drivers/base/arch_topology.c
+++ b/drivers/base/arch_topology.c
@@ -33,6 +33,11 @@ void arch_set_freq_scale(struct cpumask *cpus, unsigned long cur_freq,
 	unsigned long scale;
 	int i;
 
+	if (unlikely(!cur_freq || !max_freq)) {
+		WARN_ON_ONCE(1);
+		return;
+	}
+
 	/*
 	 * If the use of counters for FIE is enabled, just return as we don't
 	 * want to update the scale factor with information from CPUFREQ.
-- 
2.17.1