linux-kernel - [PATCH] drm/bridge: anx7625: Zero error variable when panel bridge not present

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Date:   Mon, 13 Jun 2022 12:37:05 -0400
From:   Nícolas F. R. A. Prado 
        <nfraprado@...labora.com>
To:     Robert Foss <robert.foss@...aro.org>
Cc:     kernel@...labora.com,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>,
        Nícolas F. R. A. Prado 
        <nfraprado@...labora.com>, Andrzej Hajda <andrzej.hajda@...el.com>,
        Daniel Vetter <daniel@...ll.ch>,
        David Airlie <airlied@...ux.ie>,
        Hsin-Yi Wang <hsinyi@...omium.org>,
        Jernej Skrabec <jernej.skrabec@...il.com>,
        Jonas Karlman <jonas@...boo.se>,
        José Expósito <jose.exposito89@...il.com>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        Maxime Ripard <maxime@...no.tech>,
        Neil Armstrong <narmstrong@...libre.com>,
        Sam Ravnborg <sam@...nborg.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        Tzung-Bi Shih <tzungbi@...gle.com>,
        Xin Ji <xji@...logixsemi.com>, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] drm/bridge: anx7625: Zero error variable when panel bridge not present

While parsing the DT, the anx7625 driver checks for the presence of a
panel bridge on endpoint 1. If it is missing, pdata->panel_bridge stores
the error pointer and the function returns successfully without first
cleaning that variable. This is an issue since other functions later
check for the presence of a panel bridge by testing the trueness of that
variable.

In order to ensure proper behavior, zero out pdata->panel_bridge before
returning when no panel bridge is found.

Fixes: 9e82ea0fb1df ("drm/bridge: anx7625: switch to devm_drm_of_get_bridge")
Signed-off-by: Nícolas F. R. A. Prado <nfraprado@...labora.com>

---

 drivers/gpu/drm/bridge/analogix/anx7625.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/bridge/analogix/anx7625.c b/drivers/gpu/drm/bridge/analogix/anx7625.c
index 53a5da6c49dd..3aed4de16690 100644
--- a/drivers/gpu/drm/bridge/analogix/anx7625.c
+++ b/drivers/gpu/drm/bridge/analogix/anx7625.c
@@ -1657,8 +1657,10 @@ static int anx7625_parse_dt(struct device *dev,
 
 	pdata->panel_bridge = devm_drm_of_get_bridge(dev, np, 1, 0);
 	if (IS_ERR(pdata->panel_bridge)) {
-		if (PTR_ERR(pdata->panel_bridge) == -ENODEV)
+		if (PTR_ERR(pdata->panel_bridge) == -ENODEV) {
+			pdata->panel_bridge = NULL;
 			return 0;
+		}
 
 		return PTR_ERR(pdata->panel_bridge);
 	}
-- 
2.36.1