[PATCH] mei: remove dev_err message on an unsupported ioctl

[PATCH] mei: remove dev_err message on an unsupported ioctl

[Colin King]

From: Colin Ian King <colin.king@canonical.com>

Currently the driver spams the kernel log on unsupported ioctls which is
unnecessary as the ioctl returns -ENOIOCTLCMD to indicate this anyway.
I suspect this was originally for debugging purposes but it really is not
required so remove it.

Signed-off-by: Colin Ian King <colin.king@canonical.com>
---
 drivers/misc/mei/main.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/misc/mei/main.c b/drivers/misc/mei/main.c
index 758dc73602d5..7bb013644aeb 100644
--- a/drivers/misc/mei/main.c
+++ b/drivers/misc/mei/main.c
@@ -507,7 +507,6 @@ static long mei_ioctl(struct file *file, unsigned int cmd, unsigned long data)
 		break;
 
 	default:
-		dev_err(dev->dev, ": unsupported ioctl %d.\n", cmd);
 		rets = -ENOIOCTLCMD;
 	}
 
-- 
2.15.1

RE: [PATCH] mei: remove dev_err message on an unsupported ioctl

[Winkler, Tomas]

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Re: [PATCH] mei: remove dev_err message on an unsupported ioctl

[Colin Ian King]

On 27/02/18 17:26, Winkler, Tomas wrote:
>>
>> From: Colin Ian King <colin.king@canonical.com>
>>
>> Currently the driver spams the kernel log on unsupported ioctls which is
>> unnecessary as the ioctl returns -ENOIOCTLCMD to indicate this anyway.
>> I suspect this was originally for debugging purposes but it really is not
>> required so remove it.
>>
> 
> This is rather strange as most of the legimit applications are using one IOCTL from kernel 3.0
> Do you have any reference where this call is originated from, frankly this is the first time I got such complain.

I hit this while stressing the kernel with my stress-ng kernel stressing
tool; this was not using the legitimate ioctls (to see if things
explode) and I got a rather full kernel log. So it was being abused
somewhat ;-)

> 
> In any case it would be maybe better to change it a warn once call.

Probably so, I can fix that up if that is preferred.

Colin

>  
> Thanks
> Tomas
> 
>> Signed-off-by: Colin Ian King <colin.king@canonical.com>
>> ---
>>  drivers/misc/mei/main.c | 1 -
>>  1 file changed, 1 deletion(-)
>>
>> diff --git a/drivers/misc/mei/main.c b/drivers/misc/mei/main.c index
>> 758dc73602d5..7bb013644aeb 100644
>> --- a/drivers/misc/mei/main.c
>> +++ b/drivers/misc/mei/main.c
>> @@ -507,7 +507,6 @@ static long mei_ioctl(struct file *file, unsigned int
>> cmd, unsigned long data)
>>  		break;
>>
>>  	default:
>> -		dev_err(dev->dev, ": unsupported ioctl %d.\n", cmd);
>>  		rets = -ENOIOCTLCMD;
>>  	}
>>
>> --
>> 2.15.1
> 

Re: [PATCH] mei: remove dev_err message on an unsupported ioctl

[Greg Kroah-Hartman]

On Tue, Feb 27, 2018 at 05:26:22PM +0000, Winkler, Tomas wrote:
> > 
> > From: Colin Ian King <colin.king@canonical.com>
> > 
> > Currently the driver spams the kernel log on unsupported ioctls which is
> > unnecessary as the ioctl returns -ENOIOCTLCMD to indicate this anyway.
> > I suspect this was originally for debugging purposes but it really is not
> > required so remove it.
> >
> 
> This is rather strange as most of the legimit applications are using one IOCTL from kernel 3.0
> Do you have any reference where this call is originated from, frankly this is the first time I got such complain.
> 
> In any case it would be maybe better to change it a warn once call.

Just drop the message, it should not be this easy for userspace to spam
the kernel log.  The patch looks fine to me.

thanks,

greg k-h

RE: [PATCH] mei: remove dev_err message on an unsupported ioctl

[Winkler, Tomas]

> 
> On Tue, Feb 27, 2018 at 05:26:22PM +0000, Winkler, Tomas wrote:
> > >
> > > From: Colin Ian King <colin.king@canonical.com>
> > >
> > > Currently the driver spams the kernel log on unsupported ioctls
> > > which is unnecessary as the ioctl returns -ENOIOCTLCMD to indicate this
> anyway.
> > > I suspect this was originally for debugging purposes but it really
> > > is not required so remove it.
> > >
> >
> > This is rather strange as most of the legimit applications are using
> > one IOCTL from kernel 3.0 Do you have any reference where this call is
> originated from, frankly this is the first time I got such complain.
> >
> > In any case it would be maybe better to change it a warn once call.
> 
> Just drop the message, it should not be this easy for userspace to spam the
> kernel log.  The patch looks fine to me.
> 
Fair enough, add my ack too.

Still I'm curious if this comes from the field.

Thanks
Tomas

RE: [PATCH] mei: remove dev_err message on an unsupported ioctl

[Winkler, Tomas]

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Re: [PATCH] mei: remove dev_err message on an unsupported ioctl

[Greg Kroah-Hartman]

On Tue, Feb 27, 2018 at 09:44:41PM +0000, Winkler, Tomas wrote:
> > 
> > On Tue, Feb 27, 2018 at 05:26:22PM +0000, Winkler, Tomas wrote:
> > > >
> > > > From: Colin Ian King <colin.king@canonical.com>
> > > >
> > > > Currently the driver spams the kernel log on unsupported ioctls
> > > > which is unnecessary as the ioctl returns -ENOIOCTLCMD to indicate this
> > anyway.
> > > > I suspect this was originally for debugging purposes but it really
> > > > is not required so remove it.
> > > >
> > >
> > > This is rather strange as most of the legimit applications are using
> > > one IOCTL from kernel 3.0 Do you have any reference where this call is
> > originated from, frankly this is the first time I got such complain.
> > >
> > > In any case it would be maybe better to change it a warn once call.
> > 
> > Just drop the message, it should not be this easy for userspace to spam the
> > kernel log.  The patch looks fine to me.
> > 
> Fair enough, add my ack too.
> 
> Still I'm curious if this comes from the field.

fuzzers are "in the field" :)

RE: [PATCH] mei: remove dev_err message on an unsupported ioctl

[Winkler, Tomas]

> 
> On Tue, Feb 27, 2018 at 09:44:41PM +0000, Winkler, Tomas wrote:
> > >
> > > On Tue, Feb 27, 2018 at 05:26:22PM +0000, Winkler, Tomas wrote:
> > > > >
> > > > > From: Colin Ian King <colin.king@canonical.com>
> > > > >
> > > > > Currently the driver spams the kernel log on unsupported ioctls
> > > > > which is unnecessary as the ioctl returns -ENOIOCTLCMD to
> > > > > indicate this
> > > anyway.
> > > > > I suspect this was originally for debugging purposes but it
> > > > > really is not required so remove it.
> > > > >
> > > >
> > > > This is rather strange as most of the legimit applications are
> > > > using one IOCTL from kernel 3.0 Do you have any reference where
> > > > this call is
> > > originated from, frankly this is the first time I got such complain.
> > > >
> > > > In any case it would be maybe better to change it a warn once call.
> > >
> > > Just drop the message, it should not be this easy for userspace to
> > > spam the kernel log.  The patch looks fine to me.
> > >
> > Fair enough, add my ack too.
> >
> > Still I'm curious if this comes from the field.
> 
> fuzzers are "in the field" :)

It's definitely fuzzers season.

Tomas