[PATCH v4] cpufreq/pasemi: fix an use-after-free in pas_cpufreq_cpu_init()

[Wen Yang]

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.yan...@zte.com.cn>
Cc: "Rafael J. Wysocki" <r...@rjwysocki.net>
Cc: Viresh Kumar <viresh.ku...@linaro.org>
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux...@vger.kernel.org
Cc: linux-ker...@vger.kernel.org
---
v4: restore the blank line.
v3: fix a leaked reference.
v2: clean up the code according to the advice of viresh.

 drivers/cpufreq/pasemi-cpufreq.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/cpufreq/pasemi-cpufreq.c b/drivers/cpufreq/pasemi-cpufreq.c
index 6b1e4ab..f0c98fc 100644
--- a/drivers/cpufreq/pasemi-cpufreq.c
+++ b/drivers/cpufreq/pasemi-cpufreq.c
@@ -128,20 +128,21 @@ 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)
+       if (!dn) {
+               err = -ENODEV;
                goto out;
+       }
        err = of_address_to_resource(dn, 0, &res);
        of_node_put(dn);
        if (err)
@@ -196,6 +197,7 @@ 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 +206,7 @@ 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