linux-kernel - [PATCH 5.8 431/464] cpufreq: dt: fix oops on armada37xx

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Date:   Mon, 17 Aug 2020 17:16:24 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Ivan Kokshaysky <ink@...assic.park.msu.ru>,
        Andrew Lunn <andrew@...n.ch>,
        Viresh Kumar <viresh.kumar@...aro.org>
Subject: [PATCH 5.8 431/464] cpufreq: dt: fix oops on armada37xx

From: Ivan Kokshaysky <ink@...assic.park.msu.ru>

commit 10470dec3decaf5ed3c596f85debd7c42777ae12 upstream.

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.

Cc: <stable@...r.kernel.org> # v5.7+
Signed-off-by: Ivan Kokshaysky <ink@...assic.park.msu.ru>
Reviewed-by: Andrew Lunn <andrew@...n.ch>
Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/cpufreq/armada-37xx-cpufreq.c |    1 +
 1 file changed, 1 insertion(+)

--- a/drivers/cpufreq/armada-37xx-cpufreq.c
+++ b/drivers/cpufreq/armada-37xx-cpufreq.c
@@ -456,6 +456,7 @@ static int __init armada37xx_cpufreq_dri
 	/* 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;