[PATCH] greybus: lights: check return of get_channel_from_mode

[PATCH] greybus: lights: check return of get_channel_from_mode

[Rui Miguel Silva]

If channel for the given node is not found we return null from
get_channel_from_mode. Make sure we validate the return pointer
before using it in two of the missing places.

This was originally reported in [0]:
Found by Linux Verification Center (linuxtesting.org) with SVACE.

[0] https://lore.kernel.org/all/20240301190425.120605-1-m.lobanov@rosalinux.ru

Fixes: 2870b52bae4c ("greybus: lights: add lights implementation")
Reported-by: Mikhail Lobanov <m.lobanov@rosalinux.ru>
Suggested-by: Mikhail Lobanov <m.lobanov@rosalinux.ru>
Suggested-by: Alex Elder <elder@ieee.org>
Signed-off-by: Rui Miguel Silva <rmfrfs@gmail.com>
---
 drivers/staging/greybus/light.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/staging/greybus/light.c b/drivers/staging/greybus/light.c
index c6bd86a5335a..6f10b9e2c053 100644
--- a/drivers/staging/greybus/light.c
+++ b/drivers/staging/greybus/light.c
@@ -147,6 +147,9 @@ static int __gb_lights_flash_brightness_set(struct gb_channel *channel)
 		channel = get_channel_from_mode(channel->light,
 						GB_CHANNEL_MODE_TORCH);
 
+	if (!channel)
+		return -EINVAL;
+
 	/* For not flash we need to convert brightness to intensity */
 	intensity = channel->intensity_uA.min +
 			(channel->intensity_uA.step * channel->led->brightness);
@@ -549,7 +552,8 @@ static int gb_lights_light_v4l2_register(struct gb_light *light)
 	}
 
 	channel_flash = get_channel_from_mode(light, GB_CHANNEL_MODE_FLASH);
-	WARN_ON(!channel_flash);
+	if (WARN_ON(!channel_flash))
+		return -EINVAL;
 
 	fled = &channel_flash->fled;
 
-- 
2.44.0

Re: [PATCH] greybus: lights: check return of get_channel_from_mode

[Greg Kroah-Hartman]

On Thu, Mar 07, 2024 at 09:48:13AM +0000, Rui Miguel Silva wrote:
> If channel for the given node is not found we return null from
> get_channel_from_mode. Make sure we validate the return pointer
> before using it in two of the missing places.
> 
> This was originally reported in [0]:
> Found by Linux Verification Center (linuxtesting.org) with SVACE.
> 
> [0] https://lore.kernel.org/all/20240301190425.120605-1-m.lobanov@rosalinux.ru
> 
> Fixes: 2870b52bae4c ("greybus: lights: add lights implementation")
> Reported-by: Mikhail Lobanov <m.lobanov@rosalinux.ru>
> Suggested-by: Mikhail Lobanov <m.lobanov@rosalinux.ru>
> Suggested-by: Alex Elder <elder@ieee.org>
> Signed-off-by: Rui Miguel Silva <rmfrfs@gmail.com>
> ---
>  drivers/staging/greybus/light.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/staging/greybus/light.c b/drivers/staging/greybus/light.c
> index c6bd86a5335a..6f10b9e2c053 100644
> --- a/drivers/staging/greybus/light.c
> +++ b/drivers/staging/greybus/light.c
> @@ -147,6 +147,9 @@ static int __gb_lights_flash_brightness_set(struct gb_channel *channel)
>  		channel = get_channel_from_mode(channel->light,
>  						GB_CHANNEL_MODE_TORCH);
>  
> +	if (!channel)
> +		return -EINVAL;
> +
>  	/* For not flash we need to convert brightness to intensity */
>  	intensity = channel->intensity_uA.min +
>  			(channel->intensity_uA.step * channel->led->brightness);
> @@ -549,7 +552,8 @@ static int gb_lights_light_v4l2_register(struct gb_light *light)
>  	}
>  
>  	channel_flash = get_channel_from_mode(light, GB_CHANNEL_MODE_FLASH);
> -	WARN_ON(!channel_flash);
> +	if (WARN_ON(!channel_flash))
> +		return -EINVAL;

We should NOT crash machines just because of this, the WARN_ON() should
be removed and just properly handle the error please.

thanks,

greg k-h

Re: [PATCH] greybus: lights: check return of get_channel_from_mode

[Alex Elder]

On 3/25/24 12:25 PM, Greg Kroah-Hartman wrote:
> On Thu, Mar 07, 2024 at 09:48:13AM +0000, Rui Miguel Silva wrote:
>> If channel for the given node is not found we return null from
>> get_channel_from_mode. Make sure we validate the return pointer
>> before using it in two of the missing places.
>>
>> This was originally reported in [0]:
>> Found by Linux Verification Center (linuxtesting.org) with SVACE.
>>
>> [0] https://lore.kernel.org/all/20240301190425.120605-1-m.lobanov@rosalinux.ru
>>
>> Fixes: 2870b52bae4c ("greybus: lights: add lights implementation")
>> Reported-by: Mikhail Lobanov <m.lobanov@rosalinux.ru>
>> Suggested-by: Mikhail Lobanov <m.lobanov@rosalinux.ru>
>> Suggested-by: Alex Elder <elder@ieee.org>
>> Signed-off-by: Rui Miguel Silva <rmfrfs@gmail.com>
>> ---
>>   drivers/staging/greybus/light.c | 6 +++++-
>>   1 file changed, 5 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/staging/greybus/light.c b/drivers/staging/greybus/light.c
>> index c6bd86a5335a..6f10b9e2c053 100644
>> --- a/drivers/staging/greybus/light.c
>> +++ b/drivers/staging/greybus/light.c
>> @@ -147,6 +147,9 @@ static int __gb_lights_flash_brightness_set(struct gb_channel *channel)
>>   		channel = get_channel_from_mode(channel->light,
>>   						GB_CHANNEL_MODE_TORCH);
>>   
>> +	if (!channel)
>> +		return -EINVAL;
>> +
>>   	/* For not flash we need to convert brightness to intensity */
>>   	intensity = channel->intensity_uA.min +
>>   			(channel->intensity_uA.step * channel->led->brightness);
>> @@ -549,7 +552,8 @@ static int gb_lights_light_v4l2_register(struct gb_light *light)
>>   	}
>>   
>>   	channel_flash = get_channel_from_mode(light, GB_CHANNEL_MODE_FLASH);
>> -	WARN_ON(!channel_flash);
>> +	if (WARN_ON(!channel_flash))
>> +		return -EINVAL;
> 
> We should NOT crash machines just because of this, the WARN_ON() should
> be removed and just properly handle the error please.

Greg, WARN_ON() doesn't normally crash the machine.  That said,
it's reasonable to remove the WARN_ON().

I think the purpose of the warning is that this is a case that
should "never happen," so if it does, it's making some noise.

The only caller is gb_lights_light_register(), and it checks
for an error and does "properly handle" the\ error (assuming
any error meaning "light has no flash" is correct).

Rui, please weigh in.

					-Alex


> 
> thanks,
> 
> greg k-h

Re: [PATCH] greybus: lights: check return of get_channel_from_mode

[Greg Kroah-Hartman]

On Mon, Mar 25, 2024 at 01:31:34PM -0500, Alex Elder wrote:
> On 3/25/24 12:25 PM, Greg Kroah-Hartman wrote:
> > On Thu, Mar 07, 2024 at 09:48:13AM +0000, Rui Miguel Silva wrote:
> > > If channel for the given node is not found we return null from
> > > get_channel_from_mode. Make sure we validate the return pointer
> > > before using it in two of the missing places.
> > > 
> > > This was originally reported in [0]:
> > > Found by Linux Verification Center (linuxtesting.org) with SVACE.
> > > 
> > > [0] https://lore.kernel.org/all/20240301190425.120605-1-m.lobanov@rosalinux.ru
> > > 
> > > Fixes: 2870b52bae4c ("greybus: lights: add lights implementation")
> > > Reported-by: Mikhail Lobanov <m.lobanov@rosalinux.ru>
> > > Suggested-by: Mikhail Lobanov <m.lobanov@rosalinux.ru>
> > > Suggested-by: Alex Elder <elder@ieee.org>
> > > Signed-off-by: Rui Miguel Silva <rmfrfs@gmail.com>
> > > ---
> > >   drivers/staging/greybus/light.c | 6 +++++-
> > >   1 file changed, 5 insertions(+), 1 deletion(-)
> > > 
> > > diff --git a/drivers/staging/greybus/light.c b/drivers/staging/greybus/light.c
> > > index c6bd86a5335a..6f10b9e2c053 100644
> > > --- a/drivers/staging/greybus/light.c
> > > +++ b/drivers/staging/greybus/light.c
> > > @@ -147,6 +147,9 @@ static int __gb_lights_flash_brightness_set(struct gb_channel *channel)
> > >   		channel = get_channel_from_mode(channel->light,
> > >   						GB_CHANNEL_MODE_TORCH);
> > > +	if (!channel)
> > > +		return -EINVAL;
> > > +
> > >   	/* For not flash we need to convert brightness to intensity */
> > >   	intensity = channel->intensity_uA.min +
> > >   			(channel->intensity_uA.step * channel->led->brightness);
> > > @@ -549,7 +552,8 @@ static int gb_lights_light_v4l2_register(struct gb_light *light)
> > >   	}
> > >   	channel_flash = get_channel_from_mode(light, GB_CHANNEL_MODE_FLASH);
> > > -	WARN_ON(!channel_flash);
> > > +	if (WARN_ON(!channel_flash))
> > > +		return -EINVAL;
> > 
> > We should NOT crash machines just because of this, the WARN_ON() should
> > be removed and just properly handle the error please.
> 
> Greg, WARN_ON() doesn't normally crash the machine.  That said,
> it's reasonable to remove the WARN_ON().

The huge majority of running Linux systems in the world run with
panic-on-warn enabled, including the one in your pocket :(

> I think the purpose of the warning is that this is a case that
> should "never happen," so if it does, it's making some noise.

Making noise by rebooting the box is not good.

thanks,

greg k-h

Re: [PATCH] greybus: lights: check return of get_channel_from_mode

[Alex Elder]

On 3/25/24 1:50 PM, Greg Kroah-Hartman wrote:
> On Mon, Mar 25, 2024 at 01:31:34PM -0500, Alex Elder wrote:
>> On 3/25/24 12:25 PM, Greg Kroah-Hartman wrote:
>>> On Thu, Mar 07, 2024 at 09:48:13AM +0000, Rui Miguel Silva wrote:
>>>> If channel for the given node is not found we return null from
>>>> get_channel_from_mode. Make sure we validate the return pointer
>>>> before using it in two of the missing places.
>>>>
>>>> This was originally reported in [0]:
>>>> Found by Linux Verification Center (linuxtesting.org) with SVACE.
>>>>
>>>> [0] https://lore.kernel.org/all/20240301190425.120605-1-m.lobanov@rosalinux.ru
>>>>
>>>> Fixes: 2870b52bae4c ("greybus: lights: add lights implementation")
>>>> Reported-by: Mikhail Lobanov <m.lobanov@rosalinux.ru>
>>>> Suggested-by: Mikhail Lobanov <m.lobanov@rosalinux.ru>
>>>> Suggested-by: Alex Elder <elder@ieee.org>
>>>> Signed-off-by: Rui Miguel Silva <rmfrfs@gmail.com>
>>>> ---
>>>>    drivers/staging/greybus/light.c | 6 +++++-
>>>>    1 file changed, 5 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/drivers/staging/greybus/light.c b/drivers/staging/greybus/light.c
>>>> index c6bd86a5335a..6f10b9e2c053 100644
>>>> --- a/drivers/staging/greybus/light.c
>>>> +++ b/drivers/staging/greybus/light.c
>>>> @@ -147,6 +147,9 @@ static int __gb_lights_flash_brightness_set(struct gb_channel *channel)
>>>>    		channel = get_channel_from_mode(channel->light,
>>>>    						GB_CHANNEL_MODE_TORCH);
>>>> +	if (!channel)
>>>> +		return -EINVAL;
>>>> +
>>>>    	/* For not flash we need to convert brightness to intensity */
>>>>    	intensity = channel->intensity_uA.min +
>>>>    			(channel->intensity_uA.step * channel->led->brightness);
>>>> @@ -549,7 +552,8 @@ static int gb_lights_light_v4l2_register(struct gb_light *light)
>>>>    	}
>>>>    	channel_flash = get_channel_from_mode(light, GB_CHANNEL_MODE_FLASH);
>>>> -	WARN_ON(!channel_flash);
>>>> +	if (WARN_ON(!channel_flash))
>>>> +		return -EINVAL;
>>>
>>> We should NOT crash machines just because of this, the WARN_ON() should
>>> be removed and just properly handle the error please.
>>
>> Greg, WARN_ON() doesn't normally crash the machine.  That said,
>> it's reasonable to remove the WARN_ON().
> 
> The huge majority of running Linux systems in the world run with
> panic-on-warn enabled, including the one in your pocket :(

I did not know that.  Then WARN_ON() is no better than BUG_ON().
I'm still learning.  Thank you.

					-Alex

>> I think the purpose of the warning is that this is a case that
>> should "never happen," so if it does, it's making some noise.
> 
> Making noise by rebooting the box is not good.
> 
> thanks,
> 
> greg k-h

Re: [PATCH] greybus: lights: check return of get_channel_from_mode

[Rui Miguel Silva]

Hi Greg,

Greg Kroah-Hartman <gregkh@linuxfoundation.org> writes:

> On Thu, Mar 07, 2024 at 09:48:13AM +0000, Rui Miguel Silva wrote:
>> If channel for the given node is not found we return null from
>> get_channel_from_mode. Make sure we validate the return pointer
>> before using it in two of the missing places.
>> 
>> This was originally reported in [0]:
>> Found by Linux Verification Center (linuxtesting.org) with SVACE.
>> 
>> [0] https://lore.kernel.org/all/20240301190425.120605-1-m.lobanov@rosalinux.ru
>> 
>> Fixes: 2870b52bae4c ("greybus: lights: add lights implementation")
>> Reported-by: Mikhail Lobanov <m.lobanov@rosalinux.ru>
>> Suggested-by: Mikhail Lobanov <m.lobanov@rosalinux.ru>
>> Suggested-by: Alex Elder <elder@ieee.org>
>> Signed-off-by: Rui Miguel Silva <rmfrfs@gmail.com>
>> ---
>>  drivers/staging/greybus/light.c | 6 +++++-
>>  1 file changed, 5 insertions(+), 1 deletion(-)
>> 
>> diff --git a/drivers/staging/greybus/light.c b/drivers/staging/greybus/light.c
>> index c6bd86a5335a..6f10b9e2c053 100644
>> --- a/drivers/staging/greybus/light.c
>> +++ b/drivers/staging/greybus/light.c
>> @@ -147,6 +147,9 @@ static int __gb_lights_flash_brightness_set(struct gb_channel *channel)
>>  		channel = get_channel_from_mode(channel->light,
>>  						GB_CHANNEL_MODE_TORCH);
>>  
>> +	if (!channel)
>> +		return -EINVAL;
>> +
>>  	/* For not flash we need to convert brightness to intensity */
>>  	intensity = channel->intensity_uA.min +
>>  			(channel->intensity_uA.step * channel->led->brightness);
>> @@ -549,7 +552,8 @@ static int gb_lights_light_v4l2_register(struct gb_light *light)
>>  	}
>>  
>>  	channel_flash = get_channel_from_mode(light, GB_CHANNEL_MODE_FLASH);
>> -	WARN_ON(!channel_flash);
>> +	if (WARN_ON(!channel_flash))
>> +		return -EINVAL;
>
> We should NOT crash machines just because of this, the WARN_ON() should
> be removed and just properly handle the error please.

Yeah, will move this to a less severe option (dev_err) to make some
noise about this "this should never happen" issue.

Cheers,
   Rui

> thanks,
>
> greg k-h

Re: [PATCH] greybus: lights: check return of get_channel_from_mode

[Rui Miguel Silva]

Hey Alex,

Alex Elder <elder@ieee.org> writes:

> On 3/25/24 1:50 PM, Greg Kroah-Hartman wrote:
>> On Mon, Mar 25, 2024 at 01:31:34PM -0500, Alex Elder wrote:
>>> On 3/25/24 12:25 PM, Greg Kroah-Hartman wrote:
>>>> On Thu, Mar 07, 2024 at 09:48:13AM +0000, Rui Miguel Silva wrote:
>>>>> If channel for the given node is not found we return null from
>>>>> get_channel_from_mode. Make sure we validate the return pointer
>>>>> before using it in two of the missing places.
>>>>>
>>>>> This was originally reported in [0]:
>>>>> Found by Linux Verification Center (linuxtesting.org) with SVACE.
>>>>>
>>>>> [0] https://lore.kernel.org/all/20240301190425.120605-1-m.lobanov@rosalinux.ru
>>>>>
>>>>> Fixes: 2870b52bae4c ("greybus: lights: add lights implementation")
>>>>> Reported-by: Mikhail Lobanov <m.lobanov@rosalinux.ru>
>>>>> Suggested-by: Mikhail Lobanov <m.lobanov@rosalinux.ru>
>>>>> Suggested-by: Alex Elder <elder@ieee.org>
>>>>> Signed-off-by: Rui Miguel Silva <rmfrfs@gmail.com>
>>>>> ---
>>>>>    drivers/staging/greybus/light.c | 6 +++++-
>>>>>    1 file changed, 5 insertions(+), 1 deletion(-)
>>>>>
>>>>> diff --git a/drivers/staging/greybus/light.c b/drivers/staging/greybus/light.c
>>>>> index c6bd86a5335a..6f10b9e2c053 100644
>>>>> --- a/drivers/staging/greybus/light.c
>>>>> +++ b/drivers/staging/greybus/light.c
>>>>> @@ -147,6 +147,9 @@ static int __gb_lights_flash_brightness_set(struct gb_channel *channel)
>>>>>    		channel = get_channel_from_mode(channel->light,
>>>>>    						GB_CHANNEL_MODE_TORCH);
>>>>> +	if (!channel)
>>>>> +		return -EINVAL;
>>>>> +
>>>>>    	/* For not flash we need to convert brightness to intensity */
>>>>>    	intensity = channel->intensity_uA.min +
>>>>>    			(channel->intensity_uA.step * channel->led->brightness);
>>>>> @@ -549,7 +552,8 @@ static int gb_lights_light_v4l2_register(struct gb_light *light)
>>>>>    	}
>>>>>    	channel_flash = get_channel_from_mode(light, GB_CHANNEL_MODE_FLASH);
>>>>> -	WARN_ON(!channel_flash);
>>>>> +	if (WARN_ON(!channel_flash))
>>>>> +		return -EINVAL;
>>>>
>>>> We should NOT crash machines just because of this, the WARN_ON() should
>>>> be removed and just properly handle the error please.
>>>
>>> Greg, WARN_ON() doesn't normally crash the machine.  That said,
>>> it's reasonable to remove the WARN_ON().
>> 
>> The huge majority of running Linux systems in the world run with
>> panic-on-warn enabled, including the one in your pocket :(
>
> I did not know that.  Then WARN_ON() is no better than BUG_ON().
> I'm still learning.  Thank you.

I also lost track of all this failure cascade options that normally
take the all system down.

Thanks anyway for the comments,
Cheers,
    Rui
    
>
> 					-Alex
>
>>> I think the purpose of the warning is that this is a case that
>>> should "never happen," so if it does, it's making some noise.
>> 
>> Making noise by rebooting the box is not good.
>> 
>> thanks,
>> 
>> greg k-h