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

From: Wen Yang
Date: Mon Jul 08 2019 - 03:22:30 EST


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@xxxxxxxxxx>
Cc: "Rafael J. Wysocki" <rjw@xxxxxxxxxxxxx>
Cc: Viresh Kumar <viresh.kumar@xxxxxxxxxx>
Cc: linuxppc-dev@xxxxxxxxxxxxxxxx
Cc: linux-pm@xxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
---
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