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Date:   Mon, 8 Jun 2020 14:15:19 +0200
From:   Greg KH <gregkh@linuxfoundation.org>
To:     Matthias Brugger <mbrugger@suse.com>
Cc:     matthias.bgg@kernel.org, rafael@kernel.org,
        linux-kernel@vger.kernel.org, gene.chen.richtek@gmail.com,
        lee.jones@linaro.org, kernel test robot <lkp@intel.com>
Subject: Re: [PATCH 1/2] drivers: base: Warn if driver name is not present
Message-ID: <20200608121519.GA306451@kroah.com>
References: <20200608095217.21162-1-matthias.bgg@kernel.org>
 <20200608105756.GB295073@kroah.com>
 <b8affc8c-3f38-3488-76dd-1b02fcdda329@suse.com>
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On Mon, Jun 08, 2020 at 01:48:28PM +0200, Matthias Brugger wrote:
> 
> 
> On 08/06/2020 12:57, Greg KH wrote:
> > On Mon, Jun 08, 2020 at 11:52:16AM +0200, matthias.bgg@kernel.org wrote:
> >> From: Matthias Brugger <mbrugger@suse.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@intel.com>
> >> Signed-off-by: Matthias Brugger <mbrugger@suse.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.

That driver had obviously never actually been run before :(

> 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.

Thanks, now dropped!

greg k-h