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

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Message-ID: <CAJZ5v0jtmBGOP2fBPRJr7r38iboHCa9ZyLR_smBmBNzQD2jxnQ@mail.gmail.com>
Date: Wed, 12 Nov 2025 21:25:38 +0100
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Sakari Ailus <sakari.ailus@...ux.intel.com>, Haotian Zhang <vulab@...as.ac.cn>
Cc: 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()

On Wed, Nov 12, 2025 at 3:42 PM Sakari Ailus
<sakari.ailus@...ux.intel.com> wrote:
>
> 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>

OK, applied as 6.19 material, thanks!