2019-07-17 03:58:17

by Wen Yang

Subject: [PATCH v7] 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: a9acc26b75f6 ("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: Michael Ellerman <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
---
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

2019-07-17 04:28:59

by Viresh Kumar

Subject: Re: [PATCH v7] cpufreq/pasemi: fix an use-after-free in pas_cpufreq_cpu_init()

On 17-07-19, 11:55, 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: a9acc26b75f6 ("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: Michael Ellerman <[email protected]>
> Cc: [email protected]
> Cc: [email protected]
> Cc: [email protected]
> ---
> 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(-)

Acked-by: Viresh Kumar <[email protected]>

--
viresh