linux-kernel - Re: [PATCH] ACPI: processor: Avoid NULL pointer dereferences at init time

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Date:   Wed, 16 Oct 2019 09:08:08 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     "Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:     Linux ACPI <linux-acpi@...r.kernel.org>,
        Linux PM <linux-pm@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
Subject: Re: [PATCH] ACPI: processor: Avoid NULL pointer dereferences at init
 time

On 15-10-19, 19:35, Rafael J. Wysocki wrote:
> rom: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> 
> If there are neither processor objects nor processor device objects
> in the ACPI tables, the per-CPU processors table will not be
> initialized and attempting to dereference pointers from there will
> cause the kernel to crash.  This happens in acpi_processor_ppc_init()
> and acpi_thermal_cpufreq_init() after commit d15ce412737a ("ACPI:
> cpufreq: Switch to QoS requests instead of cpufreq notifier")
> which didn't add the requisite NULL pointer checks in there.
> 
> Add the NULL pointer checks to acpi_processor_ppc_init() and
> acpi_thermal_cpufreq_init(), and to the corresponding "exit"
> routines.
> 
> While at it, drop redundant return instructions from
> acpi_processor_ppc_init() and acpi_thermal_cpufreq_init().
> 
> Fixes: d15ce412737a ("ACPI: cpufreq: Switch to QoS requests instead of cpufreq notifier")
> Reported-by: Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> ---
>  drivers/acpi/processor_perflib.c |   10 ++++++----
>  drivers/acpi/processor_thermal.c |   10 ++++++----
>  2 files changed, 12 insertions(+), 8 deletions(-)

Acked-by: Viresh Kumar <viresh.kumar@...aro.org>

-- 
viresh