Patch "cppc_cpufreq: Fix possible null pointer dereference" has been added to the 6.1-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    cppc_cpufreq: Fix possible null pointer dereference

to the 6.1-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     cppc_cpufreq-fix-possible-null-pointer-dereference.patch
and it can be found in the queue-6.1 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit f98ad68133c62c6cfb48b6eb904a62698f69ba73
Author: Aleksandr Mishin <amishin@xxxxxxxxxx>
Date:   Mon Apr 8 12:35:36 2024 +0300

    cppc_cpufreq: Fix possible null pointer dereference
    
    [ 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@xxxxxxxxxx>
    Signed-off-by: Viresh Kumar <viresh.kumar@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

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);