linux-kernel - Re: [PATCH 1/2] drivers: base: Warn if driver name is not present

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Date:   Mon, 8 Jun 2020 13:48:28 +0200
From:   Matthias Brugger <mbrugger@...e.com>
To:     Greg KH <gregkh@...uxfoundation.org>, matthias.bgg@...nel.org
Cc:     rafael@...nel.org, linux-kernel@...r.kernel.org,
        gene.chen.richtek@...il.com, lee.jones@...aro.org,
        kernel test robot <lkp@...el.com>
Subject: Re: [PATCH 1/2] drivers: base: Warn if driver name is not present



On 08/06/2020 12:57, Greg KH wrote:
> On Mon, Jun 08, 2020 at 11:52:16AM +0200, matthias.bgg@...nel.org wrote:
>> From: Matthias Brugger <mbrugger@...e.com>
>>
>> If we pass a driver without a name, we end up in a NULL pointer
>> derefernce.
> 
> That's a very good reason not to have a driver without a name :)
> 
> What in-kernel driver does this?
> 
>> Check for the name before trying to register the driver.
>> As we don't have a driver name to point to in the error message, we dump
>> the call stack to make it easier to detect the buggy driver.
>>
>> Reported-by: kernel test robot <lkp@...el.com>
>> Signed-off-by: Matthias Brugger <mbrugger@...e.com>
>> ---
>>  drivers/base/driver.c | 6 ++++++
>>  1 file changed, 6 insertions(+)
>>
>> diff --git a/drivers/base/driver.c b/drivers/base/driver.c
>> index 57c68769e157..40fba959c140 100644
>> --- a/drivers/base/driver.c
>> +++ b/drivers/base/driver.c
>> @@ -149,6 +149,12 @@ int driver_register(struct device_driver *drv)
>>  	int ret;
>>  	struct device_driver *other;
>>  
>> +	if (!drv->name) {
>> +		pr_err("Driver has no name.\n");
>> +		dump_stack();
>> +		return -EINVAL;
> 
> Ick, no, an oops-traceback for doing something dumb like this should be
> all that we need, right?
> 
> How "hardened" do we need to make internal apis anyway?  What's the odds
> that if this does trigger, the driver author would even notice it?
> 

We just had the case that a driver got accepted in a maintainer repository
without a name. Which got later found by the kernel test robot.

I agree with you that it probably doesn't make much sense to check for this kind
of bugs, as it should be discoverable if you test your code, before you submit.

I propose to ignore this patch.

Regards,
Matthias