linux-kernel - [PATCH v3 3/4] drm/ingenic: Register devm action to cleanup encoders

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Date:   Sun, 24 Jan 2021 08:55:51 +0000
From:   Paul Cercueil <paul@...pouillou.net>
To:     David Airlie <airlied@...ux.ie>, Daniel Vetter <daniel@...ll.ch>
Cc:     Sam Ravnborg <sam@...nborg.org>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        od@...c.me, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org, linux-mips@...r.kernel.org,
        Paul Cercueil <paul@...pouillou.net>, stable@...r.kernel.org
Subject: [PATCH v3 3/4] drm/ingenic: Register devm action to cleanup encoders

Since the encoders have been devm-allocated, they will be freed way
before drm_mode_config_cleanup() is called. To avoid use-after-free
conditions, we then must ensure that drm_encoder_cleanup() is called
before the encoders are freed.

v2: Use the new __drmm_simple_encoder_alloc() function

v3: Use the new drmm_plain_simple_encoder_alloc() macro

Fixes: c369cb27c267 ("drm/ingenic: Support multiple panels/bridges")
Cc: <stable@...r.kernel.org> # 5.8+
Signed-off-by: Paul Cercueil <paul@...pouillou.net>
---

Notes:
    Use the V1 of this patch to fix v5.11 and older kernels. This V3 only
    applies on the current drm-misc-next branch.

 drivers/gpu/drm/ingenic/ingenic-drm-drv.c | 15 ++++++---------
 1 file changed, 6 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/ingenic/ingenic-drm-drv.c b/drivers/gpu/drm/ingenic/ingenic-drm-drv.c
index 7bb31fbee29d..b23011c1c5d9 100644
--- a/drivers/gpu/drm/ingenic/ingenic-drm-drv.c
+++ b/drivers/gpu/drm/ingenic/ingenic-drm-drv.c
@@ -1014,20 +1014,17 @@ static int ingenic_drm_bind(struct device *dev, bool has_components)
 			bridge = devm_drm_panel_bridge_add_typed(dev, panel,
 								 DRM_MODE_CONNECTOR_DPI);
 
-		encoder = devm_kzalloc(dev, sizeof(*encoder), GFP_KERNEL);
-		if (!encoder)
-			return -ENOMEM;
+		encoder = drmm_plain_simple_encoder_alloc(drm, DRM_MODE_ENCODER_DPI);
+		if (IS_ERR(encoder)) {
+			ret = PTR_ERR(encoder);
+			dev_err(dev, "Failed to init encoder: %d\n", ret);
+			return ret;
+		}
 
 		encoder->possible_crtcs = 1;
 
 		drm_encoder_helper_add(encoder, &ingenic_drm_encoder_helper_funcs);
 
-		ret = drm_simple_encoder_init(drm, encoder, DRM_MODE_ENCODER_DPI);
-		if (ret) {
-			dev_err(dev, "Failed to init encoder: %d\n", ret);
-			return ret;
-		}
-
 		ret = drm_bridge_attach(encoder, bridge, NULL, 0);
 		if (ret) {
 			dev_err(dev, "Unable to attach bridge\n");
-- 
2.29.2