| Message ID | 20241230035714.72780-1-hanchunchao@inspur.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | cpufreq: apple-soc: Fix possible null-ptr-deref for cpufreq_cpu_get_raw() | expand |
> cpufreq_cpu_get_raw() may return NULL if the cpu is not in CPU? > policy->cpus cpu mask and it will cause null pointer dereference. … Would the summary phrase “Prevent null pointer dereference in apple_soc_cpufreq_get_rate()” be a bit nicer here? Regards, Markus
On Mon, 30 Dec 2024 03:57:14 +0000, Charles Han <hanchunchao@inspur.com> wrote: > > cpufreq_cpu_get_raw() may return NULL if the cpu is not in > policy->cpus cpu mask and it will cause null pointer dereference. > But this returned value in apple_soc_cpufreq_get_rate() is not > checked. Add NULL check in apple_soc_cpufreq_get_rate(), to handle > kernel NULL pointer dereference error. The only way I can see a CPU not having an assigned policy is when the DT is incomplete. And even then, reaching this code path doesn't look obvious to me. Can you describe how you get into this situation? Thanks, M.
diff --git a/drivers/cpufreq/apple-soc-cpufreq.c b/drivers/cpufreq/apple-soc-cpufreq.c index 4dcacab9b4bf..1c6d81355b41 100644 --- a/drivers/cpufreq/apple-soc-cpufreq.c +++ b/drivers/cpufreq/apple-soc-cpufreq.c @@ -104,6 +104,9 @@ static const struct of_device_id apple_soc_cpufreq_of_match[] __maybe_unused = { static unsigned int apple_soc_cpufreq_get_rate(unsigned int cpu) { struct cpufreq_policy *policy = cpufreq_cpu_get_raw(cpu); + if (unlikely(!policy)) + return 0; + struct apple_cpu_priv *priv = policy->driver_data; struct cpufreq_frequency_table *p; unsigned int pstate;
cpufreq_cpu_get_raw() may return NULL if the cpu is not in policy->cpus cpu mask and it will cause null pointer dereference. But this returned value in apple_soc_cpufreq_get_rate() is not checked. Add NULL check in apple_soc_cpufreq_get_rate(), to handle kernel NULL pointer dereference error. Fixes: 6286bbb40576 ("cpufreq: apple-soc: Add new driver to control Apple SoC CPU P-states") Signed-off-by: Charles Han <hanchunchao@inspur.com> --- drivers/cpufreq/apple-soc-cpufreq.c | 3 +++ 1 file changed, 3 insertions(+)