[PATCH] cpufreq: dt: fix oops on armada37xx

[PATCH] cpufreq: dt: fix oops on armada37xx

[Ivan Kokshaysky]

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;
 
-- 
2.20.1

Re: [PATCH] cpufreq: dt: fix oops on armada37xx

[Andrew Lunn]

On Sat, Jun 20, 2020 at 05:44:49PM +0100, 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>

Hi Ivan

A Fixes: tag would be good.

Reviewed-by: Andrew Lunn <andrew@lunn.ch>

    Andrew

Re: [PATCH] cpufreq: dt: fix oops on armada37xx

[Ivan Kokshaysky]

On Sat, Jun 20, 2020 at 07:54:38PM +0200, Andrew Lunn wrote:
> On Sat, Jun 20, 2020 at 05:44:49PM +0100, 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>
> 
> Hi Ivan
> 
> A Fixes: tag would be good.

Hi Andrew,

I'm not sure that "Fixes:" would be appropriate here - commit 0c868627e617
is fine by itself, it just revealed a bug in older code.

Thanks for reviewing,
Ivan.

> Reviewed-by: Andrew Lunn <andrew@lunn.ch>
> 
>     Andrew

Re: [PATCH] cpufreq: dt: fix oops on armada37xx

[Viresh Kumar]

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