2019-07-08 23:50:29

by Wen Yang

Subject: [PATCH v4] 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 <[email protected]>
Cc: "Rafael J. Wysocki" <[email protected]>
Cc: Viresh Kumar <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
---
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

2019-07-09 02:43:15

by Viresh Kumar

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

On 09-07-19, 07:39, 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 <[email protected]>
> Cc: "Rafael J. Wysocki" <[email protected]>
> Cc: Viresh Kumar <[email protected]>
> Cc: [email protected]
> Cc: [email protected]
> Cc: [email protected]
> ---
> v4: restore the blank line.

I don't find it restored in the below code.

> 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

--
viresh