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Subject[PATCH v7] cpufreq/pasemi: fix an use-after-free in pas_cpufreq_cpu_init()
Date
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@zte.com.cn>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-pm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
---
v7: adapt to commit ("cpufreq: Make cpufreq_generic_init() return void")
v6: keep the blank line and fix warning: label 'out_unmap_sdcpwr' defined but not used.
v5: put together the code to get, use, and release cpu device_node.
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 | 23 +++++++++--------------
1 file changed, 9 insertions(+), 14 deletions(-)

diff --git a/drivers/cpufreq/pasemi-cpufreq.c b/drivers/cpufreq/pasemi-cpufreq.c
index 93f39a1..c66f566 100644
--- a/drivers/cpufreq/pasemi-cpufreq.c
+++ b/drivers/cpufreq/pasemi-cpufreq.c
@@ -131,10 +131,18 @@ 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)
@@ -171,16 +179,6 @@ 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");

@@ -199,9 +197,6 @@ static int pas_cpufreq_cpu_init(struct cpufreq_policy *policy)
cpufreq_generic_init(policy, pas_freqs, get_gizmo_latency());
return 0;

-out_unmap_sdcpwr:
- iounmap(sdcpwr_mapbase);
-
out_unmap_sdcasr:
iounmap(sdcasr_mapbase);
out:
--
2.9.5
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