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

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Message-ID: <Z6DtOEPqTb_9Aqdl@smile.fi.intel.com>
Date: Mon, 3 Feb 2025 18:22:16 +0200
From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@...nel.org>,
	Danilo Krummrich <dakr@...nel.org>, Lyude Paul <lyude@...hat.com>,
	Alexander Lobakin <aleksander.lobakin@...el.com>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Jonathan Cameron <Jonathan.Cameron@...wei.com>,
	Liam Girdwood <lgirdwood@...il.com>, Lukas Wunner <lukas@...ner.de>,
	Mark Brown <broonie@...nel.org>,
	Maíra Canal <mairacanal@...eup.net>,
	Robin Murphy <robin.murphy@....com>,
	Simona Vetter <simona.vetter@...ll.ch>,
	Zijun Hu <quic_zijuhu@...cinc.com>, linux-kernel@...r.kernel.org,
	linux-usb@...r.kernel.org, rust-for-linux@...r.kernel.org
Subject: Re: [PATCH 1/3] driver core: add a faux bus for use when a simple
 device/bus is needed

On Mon, Feb 03, 2025 at 05:13:28PM +0100, Greg Kroah-Hartman wrote:
> On Mon, Feb 03, 2025 at 06:05:19PM +0200, Andy Shevchenko wrote:

...

> > > > > +	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 :)

Works for me! With printable ASCII characters it can be estimated as up to
64^256 combinations, which "ought to be enough for everybody" (of course
it will be much less if we count only human-readable strings). :-)

-- 
With Best Regards,
Andy Shevchenko