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Date:   Mon, 22 Jun 2020 07:51:37 +0530
From:   Viresh Kumar <viresh.kumar@linaro.org>
To:     Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc:     Gregory Clement <gregory.clement@bootlin.com>,
        Jason Cooper <jason@lakedaemon.net>,
        Andrew Lunn <andrew@lunn.ch>,
        Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>,
        "Rafael J. Wysocki" <rjw@rjwysocki.net>, linux-pm@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] cpufreq: dt: fix oops on armada37xx
Message-ID: <20200622022137.f27ztstb5w3o43fe@vireshk-i7>
References: <20200620164449.GA19776@mail.rc.ru>
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On 20-06-20, 17:44, Ivan Kokshaysky wrote:
> Commit 0c868627e617e43a295d8 (cpufreq: dt: Allow platform specific
> intermediate callbacks) added two function pointers to the
> struct cpufreq_dt_platform_data. However, armada37xx_cpufreq_driver_init()
> has this struct (pdata) located on the stack and uses only "suspend"
> and "resume" fields. So these newly added "get_intermediate" and
> "target_intermediate" pointers are uninitialized and contain arbitrary
> non-null values, causing all kinds of trouble.
> 
> For instance, here is an oops on espressobin after an attempt to change
> the cpefreq governor:
> 
> [   29.174554] Unable to handle kernel execute from non-executable memory at virtual address ffff00003f87bdc0
> ...
> [   29.269373] pc : 0xffff00003f87bdc0
> [   29.272957] lr : __cpufreq_driver_target+0x138/0x580
> ...
> 
> Fixed by zeroing out pdata before use.
> 
> Signed-off-by: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
> ---
>  drivers/cpufreq/armada-37xx-cpufreq.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/cpufreq/armada-37xx-cpufreq.c b/drivers/cpufreq/armada-37xx-cpufreq.c
> index aa0f06dec959..df1c941260d1 100644
> --- a/drivers/cpufreq/armada-37xx-cpufreq.c
> +++ b/drivers/cpufreq/armada-37xx-cpufreq.c
> @@ -456,6 +456,7 @@ static int __init armada37xx_cpufreq_driver_init(void)
>  	/* Now that everything is setup, enable the DVFS at hardware level */
>  	armada37xx_cpufreq_enable_dvfs(nb_pm_base);
>  
> +	memset(&pdata, 0, sizeof(pdata));
>  	pdata.suspend = armada37xx_cpufreq_suspend;
>  	pdata.resume = armada37xx_cpufreq_resume;

Applied. Thanks.

-- 
viresh