[PATCH v2] cpufreq/pasemi: fix an use-after-free in pas_cpufreq_cpu_init()

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 <redacted>
Cc: "Rafael J. Wysocki" <redacted>
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
---
v2: clean up the code according to the advice of viresh.

 drivers/cpufreq/pasemi-cpufreq.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/cpufreq/pasemi-cpufreq.c b/drivers/cpufreq/pasemi-cpufreq.c
index 6b1e4ab..c6d464b 100644
--- a/drivers/cpufreq/pasemi-cpufreq.c
+++ b/drivers/cpufreq/pasemi-cpufreq.c

@@ -128,20 +128,18 @@ static int pas_cpufreq_cpu_init(struct cpufreq_policy *policy)
 	int cur_astate, idx;
 	struct resource res;
 	struct device_node *cpu, *dn;
-	int err = -ENODEV;
+	int err;
 
 	cpu = of_get_cpu_node(policy->cpu, NULL);
-
-	of_node_put(cpu);
 	if (!cpu)
-		goto out;
+		return -ENODEV;
 
 	dn = of_find_compatible_node(NULL, NULL, "1682m-sdc");
 	if (!dn)
 		dn = of_find_compatible_node(NULL, NULL,
 					     "pasemi,pwrficient-sdc");
 	if (!dn)
-		goto out;
+		return -ENODEV;
 	err = of_address_to_resource(dn, 0, &res);
 	of_node_put(dn);
 	if (err)

@@ -196,6 +194,7 @@ static int pas_cpufreq_cpu_init(struct cpufreq_policy *policy)
 	policy->cur = pas_freqs[cur_astate].frequency;
 	ppc_proc_freq = policy->cur * 1000ul;
 
+	of_node_put(cpu);
 	return cpufreq_generic_init(policy, pas_freqs, get_gizmo_latency());
 
 out_unmap_sdcpwr:

@@ -204,6 +203,7 @@ static int pas_cpufreq_cpu_init(struct cpufreq_policy *policy)
 out_unmap_sdcasr:
 	iounmap(sdcasr_mapbase);
 out:
+	of_node_put(cpu);
 	return err;
 }
 

-- 
2.9.5

On 08-07-19, 15:19, Wen Yang wrote:

This change looks incorrect. You still need to drop reference to cpu ?

-- 
viresh

quoted

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 <redacted>
Cc: "Rafael J. Wysocki" <redacted>
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
---
v2: clean up the code according to the advice of viresh.

 drivers/cpufreq/pasemi-cpufreq.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/cpufreq/pasemi-cpufreq.c b/drivers/cpufreq/pasemi-cpufreq.c
index 6b1e4ab..c6d464b 100644
--- a/drivers/cpufreq/pasemi-cpufreq.c
+++ b/drivers/cpufreq/pasemi-cpufreq.c

@@ -128,20 +128,18 @@ static int pas_cpufreq_cpu_init(struct cpufreq_policy *policy)
     int cur_astate, idx;
     struct resource res;
     struct device_node *cpu, *dn;
-    int err = -ENODEV;
+    int err;

     cpu = of_get_cpu_node(policy->cpu, NULL);
-
-    of_node_put(cpu);
     if (!cpu)
-        goto out;
+        return -ENODEV;

quoted

     dn = of_find_compatible_node(NULL, NULL, "1682m-sdc");
     if (!dn)
         dn = of_find_compatible_node(NULL, NULL,
                          "pasemi,pwrficient-sdc");
     if (!dn)
-        goto out;
+        return -ENODEV;

This change looks incorrect. You still need to drop reference to cpu ?

Thanks!
We will fix it immediately.

--
Thanks and regards,
Wen