[PATCH] drm/bridge: ps8640: Return NULL immediately when EDID read fail

[Pin-yen Lin]

drm_edid_read returns NULL on error, so feeding it directly into
drm_edid_duplicate may lead to NULL pointer dereference. Add a check to
guard this.

Fixes: 6a17b4d1b52f ("drm/bridge: ps8640: Add a cache for EDID")
Signed-off-by: Pin-yen Lin <treapk...@chromium.org>
---

 drivers/gpu/drm/bridge/parade-ps8640.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/gpu/drm/bridge/parade-ps8640.c 
b/drivers/gpu/drm/bridge/parade-ps8640.c
index cddbfe91f75e..b823e55650b1 100644
--- a/drivers/gpu/drm/bridge/parade-ps8640.c
+++ b/drivers/gpu/drm/bridge/parade-ps8640.c
@@ -543,6 +543,7 @@ static struct edid *ps8640_bridge_get_edid(struct 
drm_bridge *bridge,
                                           struct drm_connector *connector)
 {
        struct ps8640 *ps_bridge = bridge_to_ps8640(bridge);
+       struct device *dev = &ps_bridge->page[PAGE0_DP_CNTL]->dev;
        bool poweroff = !ps_bridge->pre_enabled;
 
        if (!ps_bridge->edid) {
@@ -574,6 +575,11 @@ static struct edid *ps8640_bridge_get_edid(struct 
drm_bridge *bridge,
                                                             
connector->state->state);
        }
 
+       if (!ps_bridge->edid) {
+               dev_err(dev, "Failed to get EDID\n");
+               return NULL;
+       }
+
        return drm_edid_duplicate(ps_bridge->edid);
 }
 
-- 
2.40.0.348.gf938b09366-goog