linux-kernel - [PATCH AUTOSEL 4.4 07/17] cpufreq/pasemi: fix use-after-free in pas_cpufreq_cpu

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Message-Id: <20190802132635.14885-7-sashal@kernel.org>
Date:   Fri,  2 Aug 2019 09:26:24 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Wen Yang <wen.yang99@....com.cn>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        "Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
        Sasha Levin <sashal@...nel.org>, linuxppc-dev@...ts.ozlabs.org,
        linux-pm@...r.kernel.org
Subject: [PATCH AUTOSEL 4.4 07/17] cpufreq/pasemi: fix use-after-free in pas_cpufreq_cpu_init()

From: Wen Yang <wen.yang99@....com.cn>

[ Upstream commit e0a12445d1cb186d875410d093a00d215bec6a89 ]

The cpu variable is still being used in the of_get_property() call
after the of_node_put() call, which may result in use-after-free.

Fixes: a9acc26b75f6 ("cpufreq/pasemi: fix possible object reference leak")
Signed-off-by: Wen Yang <wen.yang99@....com.cn>
Acked-by: Viresh Kumar <viresh.kumar@...aro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/cpufreq/pasemi-cpufreq.c | 23 +++++++++--------------
 1 file changed, 9 insertions(+), 14 deletions(-)

diff --git a/drivers/cpufreq/pasemi-cpufreq.c b/drivers/cpufreq/pasemi-cpufreq.c
index 58c933f483004..991b6a3062c4f 100644
--- a/drivers/cpufreq/pasemi-cpufreq.c
+++ b/drivers/cpufreq/pasemi-cpufreq.c
@@ -145,10 +145,18 @@ static int pas_cpufreq_cpu_init(struct cpufreq_policy *policy)
 	int err = -ENODEV;
 
 	cpu = of_get_cpu_node(policy->cpu, NULL);
+	if (!cpu)
+		goto out;
 
+	max_freqp = of_get_property(cpu, "clock-frequency", NULL);
 	of_node_put(cpu);
-	if (!cpu)
+	if (!max_freqp) {
+		err = -EINVAL;
 		goto out;
+	}
+
+	/* we need the freq in kHz */
+	max_freq = *max_freqp / 1000;
 
 	dn = of_find_compatible_node(NULL, NULL, "1682m-sdc");
 	if (!dn)
@@ -185,16 +193,6 @@ static int pas_cpufreq_cpu_init(struct cpufreq_policy *policy)
 	}
 
 	pr_debug("init cpufreq on CPU %d\n", policy->cpu);
-
-	max_freqp = of_get_property(cpu, "clock-frequency", NULL);
-	if (!max_freqp) {
-		err = -EINVAL;
-		goto out_unmap_sdcpwr;
-	}
-
-	/* we need the freq in kHz */
-	max_freq = *max_freqp / 1000;
-
 	pr_debug("max clock-frequency is at %u kHz\n", max_freq);
 	pr_debug("initializing frequency table\n");
 
@@ -212,9 +210,6 @@ static int pas_cpufreq_cpu_init(struct cpufreq_policy *policy)
 
 	return cpufreq_generic_init(policy, pas_freqs, get_gizmo_latency());
 
-out_unmap_sdcpwr:
-	iounmap(sdcpwr_mapbase);
-
 out_unmap_sdcasr:
 	iounmap(sdcasr_mapbase);
 out:
-- 
2.20.1