linux-kernel - [PATCH] drm/bridge: ti-sn65dsi83: Fix null pointer dereference in remove callback

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Message-Id: <20210617111925.162120-1-net147@gmail.com>
Date:   Thu, 17 Jun 2021 21:19:25 +1000
From:   Jonathan Liu <net147@...il.com>
To:     dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Cc:     Jonathan Liu <net147@...il.com>,
        Andrzej Hajda <a.hajda@...sung.com>,
        Neil Armstrong <narmstrong@...libre.com>,
        Robert Foss <robert.foss@...aro.org>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        Jonas Karlman <jonas@...boo.se>,
        Jernej Skrabec <jernej.skrabec@...il.com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Linus Walleij <linus.walleij@...aro.org>,
        Marek Vasut <marex@...x.de>,
        Frieder Schrempf <frieder.schrempf@...tron.de>
Subject: [PATCH] drm/bridge: ti-sn65dsi83: Fix null pointer dereference in remove callback

If attach has not been called, unloading the driver can result in a null
pointer dereference in mipi_dsi_detach as ctx->dsi has not been assigned
yet.

Fixes: ceb515ba29ba6b ("drm/bridge: ti-sn65dsi83: Add TI SN65DSI83 and SN65DSI84 driver")
Signed-off-by: Jonathan Liu <net147@...il.com>
---
 drivers/gpu/drm/bridge/ti-sn65dsi83.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi83.c b/drivers/gpu/drm/bridge/ti-sn65dsi83.c
index 750f2172ef08..8e9f45c5c7c1 100644
--- a/drivers/gpu/drm/bridge/ti-sn65dsi83.c
+++ b/drivers/gpu/drm/bridge/ti-sn65dsi83.c
@@ -671,8 +671,11 @@ static int sn65dsi83_remove(struct i2c_client *client)
 {
 	struct sn65dsi83 *ctx = i2c_get_clientdata(client);
 
-	mipi_dsi_detach(ctx->dsi);
-	mipi_dsi_device_unregister(ctx->dsi);
+	if (ctx->dsi) {
+		mipi_dsi_detach(ctx->dsi);
+		mipi_dsi_device_unregister(ctx->dsi);
+	}
+
 	drm_bridge_remove(&ctx->bridge);
 	of_node_put(ctx->host_node);
 
-- 
2.32.0