Re: [PATCH] i3c: fix refcount inconsistency in i3c_master_register

[Shuhao Fu <sfual@cse.ust.hk>]

On Thu, Oct 09, 2025 at 12:17:11PM -0400, Frank Li wrote:
> On Wed, Oct 08, 2025 at 03:27:09PM +0800, Shuhao Fu wrote:
> > In `i3c_master_register`, a possible refcount inconsistency has been
> > identified, causing possible resource leak.
> >
> > Function `of_node_get` increases the refcount of `parent->of_node`. If
> > function `i3c_bus_init` fails, the function returns immediately without
> > a corresponding decrease, resulting in an inconsistent refcounter.
> >
> > In this patch, an extra goto label is added to ensure the balance of
> > refcount when `i3c_bus_init` fails.
> >
> > Fixes: 3a379bbcea0a ("i3c: Add core I3C infrastructure")
> > Signed-off-by: Shuhao Fu <sfual@cse.ust.hk>
> > ---
> >  drivers/i3c/master.c | 5 ++++-
> >  1 file changed, 4 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/i3c/master.c b/drivers/i3c/master.c
> > index d946db75d..9f4fe98d2 100644
> > --- a/drivers/i3c/master.c
> > +++ b/drivers/i3c/master.c
> > @@ -2885,7 +2885,7 @@ int i3c_master_register(struct i3c_master_controller *master,
> >
> >  	ret = i3c_bus_init(i3cbus, master->dev.of_node);
> >  	if (ret)
> > -		return ret;
> > +		goto err_put_of_node;
> 
> I think it'd better to set release function for master dev to release
> of_node because of_node_put() also missed at i3c_master_unregister()
> 
> you can refer drivers/base/platform.c
> 
> Frank

Do you mean that we should do `of_node_release` in
`platform_device_release`, instead of respecting the refcounting via
`of_node_put`? 

> 
> >
> >  	device_initialize(&master->dev);
> >  	dev_set_name(&master->dev, "i3c-%d", i3cbus->id);
> > @@ -2973,6 +2973,9 @@ int i3c_master_register(struct i3c_master_controller *master,
> >  err_put_dev:
> >  	put_device(&master->dev);
> >
> > +err_put_of_node:
> > +	of_node_put(master->dev.of_node);
> > +
> >  	return ret;
> >  }
> >  EXPORT_SYMBOL_GPL(i3c_master_register);
> > --
> > 2.39.5 (Apple Git-154)
> >
> >
> > --
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