[PATCH 4.19 158/168] cpufreq: dt: fix oops on armada37xx

Greg Kroah-Hartman
2020-08-17T17:37:38Z

From: Ivan Kokshaysky <ink@jurassic.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@vger.kernel.org> # v5.7+
Signed-off-by: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.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
@@ -458,6 +458,7 @@ 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;