Re: [PATCH v2] ACPI: CPPC: Add NULL pointer check to cppc_get_perf()

Kai-Heng Feng
2021-11-24T07:46:50Z

On Thu, Nov 18, 2021 at 9:37 PM Rafael J. Wysocki <rjw@rjwysocki.net> wrote:
>
> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> Subject: [PATCH] ACPI: CPPC: Add NULL pointer check to cppc_get_perf()
>
> Check cpc_desc against NULL in cppc_get_perf(), so it doesn't crash
> down the road if cpc_desc is NULL.
>
> Fixes: 0654cf05d17b ("ACPI: CPPC: Introduce cppc_get_nominal_perf()")
> Reported-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> Cc: 5.15+ <stable@vger.kernel.org> # 5.15+

Sorry for the late test, I bricked my previous ADL rig.
Tested-by: Kai-Heng Feng <kai.heng.feng@canonical.com>

> ---
>
> -> v2: Check cpc_desc against NULL before using it to initialize reg.
>
> ---
> drivers/acpi/cppc_acpi.c | 9 ++++++++-
> 1 file changed, 8 insertions(+), 1 deletion(-)
>
> Index: linux-pm/drivers/acpi/cppc_acpi.c
> ===================================================================
> --- linux-pm.orig/drivers/acpi/cppc_acpi.c
> +++ linux-pm/drivers/acpi/cppc_acpi.c
> @@ -998,7 +998,14 @@ static int cpc_write(int cpu, struct cpc
> static int cppc_get_perf(int cpunum, enum cppc_regs reg_idx, u64 *perf)
> {
> struct cpc_desc *cpc_desc = per_cpu(cpc_desc_ptr, cpunum);
> - struct cpc_register_resource *reg = &cpc_desc->cpc_regs[reg_idx];
> + struct cpc_register_resource *reg;
> +
> + if (!cpc_desc) {
> + pr_debug("No CPC descriptor for CPU:%d\n", cpunum);
> + return -ENODEV;
> + }
> +
> + reg = &cpc_desc->cpc_regs[reg_idx];
>
> if (CPC_IN_PCC(reg)) {
> int pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, cpunum);
>
>
>