linux-kernel - [PATCH v2] drm/mediatek: Clean dangling pointer on bind error path

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Message-Id: <20221122143949.3493104-1-nfraprado@collabora.com>
Date:   Tue, 22 Nov 2022 09:39:49 -0500
From:   Nícolas F. R. A. Prado 
        <nfraprado@...labora.com>
To:     Chun-Kuang Hu <chunkuang.hu@...nel.org>
Cc:     kernel@...labora.com, "Nancy . Lin" <nancy.lin@...iatek.com>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>,
        Nícolas F. R. A. Prado 
        <nfraprado@...labora.com>, CK Hu <ck.hu@...iatek.com>,
        Daniel Kurtz <djkurtz@...omium.org>,
        Daniel Vetter <daniel@...ll.ch>,
        David Airlie <airlied@...il.com>,
        Mao Huang <littlecvr@...omium.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        YT Shen <yt.shen@...iatek.com>,
        dri-devel@...ts.freedesktop.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-mediatek@...ts.infradead.org
Subject: [PATCH v2] drm/mediatek: Clean dangling pointer on bind error path

mtk_drm_bind() can fail, in which case drm_dev_put() is called,
destroying the drm_device object. However a pointer to it was still
being held in the private object, and that pointer would be passed along
to DRM in mtk_drm_sys_prepare() if a suspend were triggered at that
point, resulting in a panic. Clean the pointer when destroying the
object in the error path to prevent this from happening.

Fixes: 119f5173628a ("drm/mediatek: Add DRM Driver for Mediatek SoC MT8173.")
Signed-off-by: Nícolas F. R. A. Prado <nfraprado@...labora.com>

---

Changes in v2:
- Added Fixes tag

 drivers/gpu/drm/mediatek/mtk_drm_drv.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/gpu/drm/mediatek/mtk_drm_drv.c b/drivers/gpu/drm/mediatek/mtk_drm_drv.c
index 39a42dc8fb85..a21ff1b3258c 100644
--- a/drivers/gpu/drm/mediatek/mtk_drm_drv.c
+++ b/drivers/gpu/drm/mediatek/mtk_drm_drv.c
@@ -514,6 +514,7 @@ static int mtk_drm_bind(struct device *dev)
 err_deinit:
 	mtk_drm_kms_deinit(drm);
 err_free:
+	private->drm = NULL;
 	drm_dev_put(drm);
 	return ret;
 }
-- 
2.38.1