linux-kernel - Re: [PATCH] ACPI: property: Fix fwnode refcount leak in acpi_fwnode_graph_parse

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Message-ID: <aRSczeIXvymTQN3D@kekkonen.localdomain>
Date: Wed, 12 Nov 2025 16:42:21 +0200
From: Sakari Ailus <sakari.ailus@...ux.intel.com>
To: "Rafael J. Wysocki" <rafael@...nel.org>
Cc: Haotian Zhang <vulab@...as.ac.cn>,
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ACPI: property: Fix fwnode refcount leak in
 acpi_fwnode_graph_parse_endpoint()

Hi Rafael, Haotian,

On Wed, Nov 12, 2025 at 02:48:30PM +0100, Rafael J. Wysocki wrote:
> On Tue, Nov 11, 2025 at 8:50 AM Haotian Zhang <vulab@...as.ac.cn> wrote:
> >
> > acpi_fwnode_graph_parse_endpoint() calls fwnode_get_parent() to obtain the
> > parent fwnode but returns without calling fwnode_handle_put() on it. This
> > leads to a fwnode refcount leak and prevents the parent node from being
> > released properly.
> >
> > Call fwnode_handle_put() on the parent fwnode before returning to
> > fix the leak.
> >
> > Fixes: 3b27d00e7b6d ("device property: Move fwnode graph ops to firmware specific locations")
> > Signed-off-by: Haotian Zhang <vulab@...as.ac.cn>
> > ---
> >  drivers/acpi/property.c | 1 +
> >  1 file changed, 1 insertion(+)
> >
> > diff --git a/drivers/acpi/property.c b/drivers/acpi/property.c
> > index 1b997a5497e7..7f8790e8dc4e 100644
> > --- a/drivers/acpi/property.c
> > +++ b/drivers/acpi/property.c
> > @@ -1714,6 +1714,7 @@ static int acpi_fwnode_graph_parse_endpoint(const struct fwnode_handle *fwnode,
> >         if (fwnode_property_read_u32(fwnode, "reg", &endpoint->id))
> >                 fwnode_property_read_u32(fwnode, "endpoint", &endpoint->id);
> >
> > +       fwnode_handle_put(port_fwnode);

I'd add a newline here.

> >         return 0;
> >  }
> >
> > --
> 
> Andy, Sakari, this looks like a genuine fix to me, any comments?

Thanks for cc'ing me.

On ACPI fwnode_handle_put() is a nop, and presumably a parent of an ACPI
node is an ACPI node as well. So this doesn't change fwnode refcounting but
is nevertheless a good thing to do for API usage correctness.

Reviewed-by: Sakari Ailus <sakari.ailus@...ux.intel.com>

-- 
Kind regards,

Sakari Ailus