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From:   Wen Yang <wen.yang99@zte.com.cn>
To:     linux-kernel@vger.kernel.org
Cc:     xue.zhihong@zte.com.cn, wang.yi59@zte.com.cn,
        cheng.shengyu@zte.com.cn, Wen Yang <wen.yang99@zte.com.cn>,
        "Rafael J. Wysocki" <rjw@rjwysocki.net>,
        Viresh Kumar <viresh.kumar@linaro.org>,
        linuxppc-dev@lists.ozlabs.org, linux-pm@vger.kernel.org
Subject: [PATCH] cpufreq/pasemi: fix an use-after-free in pas_cpufreq_cpu_init()
Date:   Mon, 8 Jul 2019 14:19:02 +0800
Message-Id: <1562566745-7447-1-git-send-email-wen.yang99@zte.com.cn>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

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: a9acc26b75f ("cpufreq/pasemi: fix possible object reference leak")
Signed-off-by: Wen Yang <wen.yang99@zte.com.cn>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-pm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
---
 drivers/cpufreq/pasemi-cpufreq.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/cpufreq/pasemi-cpufreq.c b/drivers/cpufreq/pasemi-cpufreq.c
index 6b1e4ab..d2dd47b 100644
--- a/drivers/cpufreq/pasemi-cpufreq.c
+++ b/drivers/cpufreq/pasemi-cpufreq.c
@@ -132,7 +132,6 @@ static int pas_cpufreq_cpu_init(struct cpufreq_policy *policy)
 
 	cpu = of_get_cpu_node(policy->cpu, NULL);
 
-	of_node_put(cpu);
 	if (!cpu)
 		goto out;
 
@@ -141,15 +140,15 @@ static int pas_cpufreq_cpu_init(struct cpufreq_policy *policy)
 		dn = of_find_compatible_node(NULL, NULL,
 					     "pasemi,pwrficient-sdc");
 	if (!dn)
-		goto out;
+		goto out_put_cpu_node;
 	err = of_address_to_resource(dn, 0, &res);
 	of_node_put(dn);
 	if (err)
-		goto out;
+		goto out_put_cpu_node;
 	sdcasr_mapbase = ioremap(res.start + SDCASR_OFFSET, 0x2000);
 	if (!sdcasr_mapbase) {
 		err = -EINVAL;
-		goto out;
+		goto out_put_cpu_node;
 	}
 
 	dn = of_find_compatible_node(NULL, NULL, "1682m-gizmo");
@@ -177,6 +176,7 @@ static int pas_cpufreq_cpu_init(struct cpufreq_policy *policy)
 		err = -EINVAL;
 		goto out_unmap_sdcpwr;
 	}
+	of_node_put(cpu);
 
 	/* we need the freq in kHz */
 	max_freq = *max_freqp / 1000;
@@ -203,6 +203,8 @@ static int pas_cpufreq_cpu_init(struct cpufreq_policy *policy)
 
 out_unmap_sdcasr:
 	iounmap(sdcasr_mapbase);
+out_put_cpu_node:
+	of_node_put(cpu);
 out:
 	return err;
 }
-- 
2.9.5