Re: [PATCH] serial: 8250-dw: unregister 8250 port if clk_notifier_register() fails

[Andy Shevchenko]

On Wed, May 13, 2026 at 11:34:58PM +0300, Andy Shevchenko wrote:
> On Wed, May 13, 2026 at 08:05:03PM +0500, Stepan Ionichev wrote:

Also note, the Subject prefix should be "serial: 8250_dw: ...".

> > dw8250_probe() registers the 8250 port via serial8250_register_8250_port()
> > and then, if the device has a clock, registers a clock notifier:
> > 
> > 	data->data.line = serial8250_register_8250_port(up);
> > 	if (data->data.line < 0)
> > 		return data->data.line;
> > 	...
> > 	if (data->clk) {
> > 		err = clk_notifier_register(data->clk, &data->clk_notifier);
> > 		if (err)
> > 			return dev_err_probe(dev, err,
> > 					     "Failed to set the clock notifier\n");
> > 		...
> > 	}
> > 
> > If clk_notifier_register() fails, probe returns the error but leaves
> > the 8250 port registered. The matching serial8250_unregister_port()
> > lives in dw8250_remove(), which is not called when probe fails, so
> > the port slot in the serial8250 array stays occupied until the
> > device is rebound or the system is rebooted. The devm-allocated
> > driver data is freed while the port still references it (via the
> > saved private_data and serial_in/serial_out callbacks), so any
> > access to that port slot before a rebind would be a use-after-free.
> > 
> > Unregister the port on the clk_notifier_register() error path.
> 
> Maybe as a fix for backporting. For the current cycle can you remove that
> notifier and all that crap that was brought by Baikal upstreaming which won't
> ever be finished (as we actually dropped Baikal code in the kernel)?
> 
> Or maybe series of two: this one as backport and the other one as fix / remove
> Baikal support entirely from this driver.

-- 
With Best Regards,
Andy Shevchenko