[PATCH 6.1 127/473] cppc_cpufreq: Fix possible null pointer dereference

Greg Kroah-Hartman
2024-06-06T14:14:11Z

From: Aleksandr Mishin <amishin@t-argos.ru>

[ Upstream commit cf7de25878a1f4508c69dc9f6819c21ba177dbfe ]

cppc_cpufreq_get_rate() and hisi_cppc_cpufreq_get_rate() can be called from
different places with various parameters. So cpufreq_cpu_get() can return
null as 'policy' in some circumstances.
Fix this bug by adding null return check.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: a28b2bfc099c ("cppc_cpufreq: replace per-cpu data array with a list")
Signed-off-by: Aleksandr Mishin <amishin@t-argos.ru>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/cpufreq/cppc_cpufreq.c | 14 ++++++++++++--
1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/drivers/cpufreq/cppc_cpufreq.c b/drivers/cpufreq/cppc_cpufreq.c
index 022e3555407c8..8791a88c7741c 100644
--- a/drivers/cpufreq/cppc_cpufreq.c
+++ b/drivers/cpufreq/cppc_cpufreq.c
@@ -841,10 +841,15 @@ static unsigned int cppc_cpufreq_get_rate(unsigned int cpu)
{
struct cppc_perf_fb_ctrs fb_ctrs_t0 = {0}, fb_ctrs_t1 = {0};
struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
- struct cppc_cpudata *cpu_data = policy->driver_data;
+ struct cppc_cpudata *cpu_data;
u64 delivered_perf;
int ret;

+ if (!policy)
+ return -ENODEV;
+
+ cpu_data = policy->driver_data;
+
cpufreq_cpu_put(policy);

ret = cppc_get_perf_ctrs(cpu, &fb_ctrs_t0);
@@ -924,10 +929,15 @@ static struct cpufreq_driver cppc_cpufreq_driver = {
static unsigned int hisi_cppc_cpufreq_get_rate(unsigned int cpu)
{
struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
- struct cppc_cpudata *cpu_data = policy->driver_data;
+ struct cppc_cpudata *cpu_data;
u64 desired_perf;
int ret;

+ if (!policy)
+ return -ENODEV;
+
+ cpu_data = policy->driver_data;
+
cpufreq_cpu_put(policy);

ret = cppc_get_desired_perf(cpu, &desired_perf);
--
2.43.0