[PATCH v7 1/3] drm: adv7511: Fix use-after-free in adv7533_attach_dsi()

[Biju Das]

The host_node pointer was assigned and freed in adv7533_parse_dt(), and
later, adv7533_attach_dsi() uses the same. Fix this use-after-free issue
by dropping of_node_put() in adv7533_parse_dt() and calling of_node_put()
in error path of probe() and also in the remove().

Fixes: 1e4d58cd7f88 ("drm/bridge: adv7533: Create a MIPI DSI device")
Cc: stable at vger.kernel.org
Reviewed-by: Laurent Pinchart <laurent.pinchart+renesas at ideasonboard.com>
Signed-off-by: Biju Das <biju.das.jz at bp.renesas.com>
---
Changes in v7:
 - Dropped check for host_node as of_node_put() is a no-op when called
   with a NULL pointer. 
 - Added Rb tag from Laurent.
Changes in v6:
 - Fixed memory leak by adding goto stattement in error path of
   adv7511_init_regulators().
Changes in v5:
 - Updated commit description.
 - restored host_node in struct adv7511.
 - Dropped of_node_put() in adv7533_parse_dt() and calling of_node_put()
   in error path of probe() and also in the remove().
Changes in v4:
 - Updated commit description.
 - Dropped host_node from struct adv7511 and instead used a local pointer
   in probe(). Also freeing of host_node pointer after use is done in
   probe().
Changes in v3:
 - Replace __free construct with readable of_node_put().
Changes in v2:
 - Added the tag "Cc: stable at vger.kernel.org" in the sign-off area.
 - Dropped Archit Taneja invalid Mail address
---
 drivers/gpu/drm/bridge/adv7511/adv7511_drv.c | 10 ++++++++--
 drivers/gpu/drm/bridge/adv7511/adv7533.c     |  2 --
 2 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
index eb5919b38263..a13b3d8ab6ac 100644
--- a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
+++ b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
@@ -1241,8 +1241,10 @@ static int adv7511_probe(struct i2c_client *i2c)
 		return ret;
 
 	ret = adv7511_init_regulators(adv7511);
-	if (ret)
-		return dev_err_probe(dev, ret, "failed to init regulators\n");
+	if (ret) {
+		dev_err_probe(dev, ret, "failed to init regulators\n");
+		goto err_of_node_put;
+	}
 
 	/*
 	 * The power down GPIO is optional. If present, toggle it from active to
@@ -1363,6 +1365,8 @@ static int adv7511_probe(struct i2c_client *i2c)
 	i2c_unregister_device(adv7511->i2c_edid);
 uninit_regulators:
 	adv7511_uninit_regulators(adv7511);
+err_of_node_put:
+	of_node_put(adv7511->host_node);
 
 	return ret;
 }
@@ -1371,6 +1375,8 @@ static void adv7511_remove(struct i2c_client *i2c)
 {
 	struct adv7511 *adv7511 = i2c_get_clientdata(i2c);
 
+	of_node_put(adv7511->host_node);
+
 	adv7511_uninit_regulators(adv7511);
 
 	drm_bridge_remove(&adv7511->bridge);
diff --git a/drivers/gpu/drm/bridge/adv7511/adv7533.c b/drivers/gpu/drm/bridge/adv7511/adv7533.c
index 4481489aaf5e..5f195e91b3e6 100644
--- a/drivers/gpu/drm/bridge/adv7511/adv7533.c
+++ b/drivers/gpu/drm/bridge/adv7511/adv7533.c
@@ -181,8 +181,6 @@ int adv7533_parse_dt(struct device_node *np, struct adv7511 *adv)
 	if (!adv->host_node)
 		return -ENODEV;
 
-	of_node_put(adv->host_node);
-
 	adv->use_timing_gen = !of_property_read_bool(np,
 						"adi,disable-timing-generator");
 
-- 
2.43.0