Re: [PATCH 1/3] driver core: add a faux bus for use when a simple device/bus is needed

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Mon, Feb 03, 2025 at 06:05:19PM +0200, Andy Shevchenko wrote:
> > > > +/**
> > > > + * __faux_device_create - create and register a faux device and driver
> > > > + * @name: name of the device and driver we are adding
> > > > + * @faux_ops: struct faux_driver_ops that the new device will call back into, can be NULL
> > > > + * @owner: module owner of the device/driver
> > > > + *
> > > > + * Create a new faux device and driver, both with the same name, and register
> > > > + * them in the driver core properly.  The probe() callback of @faux_ops will be
> > > > + * called with the new device that is created for the caller to do something
> > > > + * with.
> > > 
> > > The kernel-doc will complain on missing Return: section.
> > 
> > Is that new?  Does that mean platform.c has lots of complaints in it as
> > well?  What does platform_find_device_by_driver() give you for a
> > documentation issue?
> > 
> > And as I didn't hook this up to the kernel documentation build yet, it
> > shouldn't produce any warnings anywhere :)
> 
> I would rather say it's old.
> 
> Run
> 
> 	kernel-doc -Wall -none -v ...your file...
> 
> and find the warning. During the kernel builds this is moved to extra warnings.

Ah, nice, didn't know about that.  Now fixed up.

> > > > + */
> 
> ...
> 
> > > > +	faux_obj = kzalloc(sizeof(*faux_obj) + strlen(name) + 1, GFP_KERNEL);
> > > 
> > > Potential overflow. To avoid one may use struct_size() from overflow.h.
> > 
> > Users should not be providing the string here.  Again, this comes from
> > platform.c.
> 
> I'm not sure I follow. The name parameter is not limited anyhow, so one may
> provide non-terminated string and strlen() will return an arbitrary number.
> Potentially this can lead to big numbers and become an overflow when gets
> to a parameter for kmalloc(). This most likely never happen in real life,
> but still the overflow is possible.

I've now bounded at 256, because really, who needs a bigger name for a
device than that :)

thanks,

greg k-h