[PATCH] drm/bridge: display-connector: implement the error path of .probe()

[Joe Hattori]

Hi Laurent,

Thank you for your review.

On Fri, Dec 13, 2024 at 6:33 PM Laurent Pinchart
<laurent.pinchart at ideasonboard.com> wrote:
>
> Hi Joe,
>
> Thank you for the patch.
>
> On Fri, Dec 13, 2024 at 05:15:50PM +0900, Joe Hattori wrote:
> > Current implementation of .probe() leaks a reference of i2c_adapter.
> > Implement an error path and call put_device() on the obtained
> > i2c_adapter in it to fix this refcount bug.
> >
> > This bug was found by an experimental static analysis tool that I am
> > developing.
> >
> > Fixes: 0c275c30176b ("drm/bridge: Add bridge driver for display connectors")
> > Signed-off-by: Joe Hattori <joe at pf.is.s.u-tokyo.ac.jp>
> > ---
> >  drivers/gpu/drm/bridge/display-connector.c | 25 ++++++++++++++++------
> >  1 file changed, 19 insertions(+), 6 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/bridge/display-connector.c b/drivers/gpu/drm/bridge/display-connector.c
> > index 72bc508d4e6e..84f1c3798d32 100644
> > --- a/drivers/gpu/drm/bridge/display-connector.c
> > +++ b/drivers/gpu/drm/bridge/display-connector.c
> > @@ -332,8 +332,11 @@ static int display_connector_probe(struct platform_device *pdev)
> >               int ret;
> >
> >               ret = display_connector_get_supply(pdev, conn, "dp-pwr");
> > -             if (ret < 0)
> > -                     return dev_err_probe(&pdev->dev, ret, "failed to get DP PWR regulator\n");
> > +             if (ret < 0) {
> > +                     ret = dev_err_probe(&pdev->dev, ret,
> > +                                         "failed to get DP PWR regulator\n");
> > +                     goto err_put;
> > +             }
> >       }
> >
> >       /* enable DDC */
> > @@ -345,19 +348,24 @@ static int display_connector_probe(struct platform_device *pdev)
> >
> >               if (IS_ERR(conn->ddc_en)) {
> >                       dev_err(&pdev->dev, "Couldn't get ddc-en gpio\n");
> > -                     return PTR_ERR(conn->ddc_en);
> > +                     ret = PTR_ERR(conn->ddc_en);
> > +                     goto err_put;
> >               }
> >
> >               ret = display_connector_get_supply(pdev, conn, "hdmi-pwr");
> > -             if (ret < 0)
> > -                     return dev_err_probe(&pdev->dev, ret, "failed to get HDMI +5V Power regulator\n");
> > +             if (ret < 0) {
> > +                     ret = dev_err_probe(
> > +                             &pdev->dev, ret,
> > +                             "failed to get HDMI +5V Power regulator\n");
>
>                         ret = dev_err_probe(&pdev->dev, ret,
>                                             "failed to get HDMI +5V Power regulator\n");
>
> > +                     goto err_put;
> > +             }
> >       }
> >
> >       if (conn->supply) {
> >               ret = regulator_enable(conn->supply);
> >               if (ret) {
> >                       dev_err(&pdev->dev, "failed to enable PWR regulator: %d\n", ret);
> > -                     return ret;
> > +                     goto err_put;
> >               }
> >       }
> >
> > @@ -383,6 +391,11 @@ static int display_connector_probe(struct platform_device *pdev)
> >       drm_bridge_add(&conn->bridge);
> >
> >       return 0;
> > +
> > +err_put:
> > +     if (conn->bridge.ddc)
>
> i2c_put_adapter() already has a NULL check.

Yes, fixed in the v2 patch.

>
> > +             i2c_put_adapter(conn->bridge.ddc);
> > +     return ret;
> >  }
> >
> >  static void display_connector_remove(struct platform_device *pdev)
>
> --
> Regards,
>
> Laurent Pinchart

Best,
Joe