[PATCH v3] cpufreq/pasemi: fix an use-after-free inpas_cpufreq_cpu_init()

[Christian Zigotzky]

Is a final patch available for testing? Please do not release it without 
testing.

- Christian

On 09-07-19, 16:04, Wen Yang wrote:
 > 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 at zte.com.cn>
 > Cc: "Rafael J. Wysocki" <rjw at rjwysocki.net>
 > Cc: Viresh Kumar <viresh.kumar at linaro.org>
 > Cc: Michael Ellerman <mpe at ellerman.id.au>
 > Cc: linuxppc-dev at lists.ozlabs.org
 > Cc: linux-pm at vger.kernel.org
 > Cc: linux-kernel at vger.kernel.org
 > ---
 > 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 | 21 +++++++++------------
 >  1 file changed, 9 insertions(+), 12 deletions(-)
 >
 > diff --git a/drivers/cpufreq/pasemi-cpufreq.c 
b/drivers/cpufreq/pasemi-cpufreq.c
 > index 6b1e4ab..1f0beb7 100644
 > --- a/drivers/cpufreq/pasemi-cpufreq.c
 > +++ b/drivers/cpufreq/pasemi-cpufreq.c
 > @@ -131,10 +131,17 @@ static int pas_cpufreq_cpu_init(struct 
cpufreq_policy *policy)
 >      int err = -ENODEV;
 >
 >      cpu = of_get_cpu_node(policy->cpu, NULL);
 > -
 > -    of_node_put(cpu);
 >      if (!cpu)
 >          goto out;

I would have loved a blank line here :)

 > +    max_freqp = of_get_property(cpu, "clock-frequency", NULL);
 > +    of_node_put(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 +178,6 @@ 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");

Though, enough versions have happened now.

Acked-by: Viresh Kumar <viresh.kumar at linaro.org>

-- 
viresh