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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        "=?UTF-8?q?N=C3=ADcolas=20F . =20R . =20A . =20Prado?=" 
        <nfraprado@collabora.com>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@collabora.com>,
        Robert Foss <robert.foss@linaro.org>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.19 0359/1157] drm/bridge: anx7625: Zero error variable when panel bridge not present
Date:   Mon, 15 Aug 2022 19:55:15 +0200
Message-Id: <20220815180454.076004289@linuxfoundation.org>
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From: Nícolas F. R. A. Prado <nfraprado@collabora.com>

[ Upstream commit 3f49f7591e7150c502aa8d04354941ec2394153f ]

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@collabora.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: Robert Foss <robert.foss@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20220613163705.1531721-1-nfraprado@collabora.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 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 01f46d9189c1..0117fd8c62ae 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);
 	}
-- 
2.35.1