[PATCH] drm/panel: Fix a possible null-pointer dereference in jdi_panel_dsi_remove()

[Tuo Li]

In jdi_panel_dsi_remove(), jdi is explicitly checked, indicating that it
may be NULL:

  if (!jdi)
    mipi_dsi_detach(dsi);

However, when jdi is NULL, the function does not return and continues by
calling jdi_panel_disable():

  err = jdi_panel_disable(&jdi->base);

Inside jdi_panel_disable(), jdi is dereferenced unconditionally, which can
lead to a NULL-pointer dereference:

  struct jdi_panel *jdi = to_panel_jdi(panel);
  backlight_disable(jdi->backlight);

To prevent such a potential NULL-pointer dereference, return early from
jdi_panel_dsi_remove() when jdi is NULL.

Signed-off-by: Tuo Li <isli...@gmail.com>
---
 drivers/gpu/drm/panel/panel-jdi-lpm102a188a.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/panel/panel-jdi-lpm102a188a.c 
b/drivers/gpu/drm/panel/panel-jdi-lpm102a188a.c
index 23462065d726..ea975170faff 100644
--- a/drivers/gpu/drm/panel/panel-jdi-lpm102a188a.c
+++ b/drivers/gpu/drm/panel/panel-jdi-lpm102a188a.c
@@ -434,8 +434,10 @@ static void jdi_panel_dsi_remove(struct mipi_dsi_device 
*dsi)
        int err;
 
        /* only detach from host for the DSI-LINK2 interface */
-       if (!jdi)
+       if (!jdi) {
                mipi_dsi_detach(dsi);
+               return;
+       }
 
        err = jdi_panel_disable(&jdi->base);
        if (err < 0)
-- 
2.43.0