linux-kernel - [PATCH 2/2] drm/imx: make sure to cleanup DRM before unbinding components

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Date:   Tue,  9 Oct 2018 23:30:49 +0200
From:   Stefan Agner <stefan@...er.ch>
To:     p.zabel@...gutronix.de, airlied@...ux.ie,
        gregkh@...uxfoundation.org
Cc:     rafael@...nel.org, linux@...linux.org.uk,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        Stefan Agner <stefan@...er.ch>
Subject: [PATCH 2/2] drm/imx: make sure to cleanup DRM before unbinding components

In situations where a component fails to bind, a previously
successfully bound component might already registered itself
with the DRM framework (e.g. an encoder). When the master
component then calls drm_mode_config_cleanup, we end up in a
use after free sitution.

Use the cleanup callback to make sure all framework level
cleanup is done by the time we unbind components.

Signed-off-by: Stefan Agner <stefan@...er.ch>
---
 drivers/gpu/drm/imx/imx-drm-core.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/imx/imx-drm-core.c b/drivers/gpu/drm/imx/imx-drm-core.c
index 5ea0c82f9957..b174a0ca9acb 100644
--- a/drivers/gpu/drm/imx/imx-drm-core.c
+++ b/drivers/gpu/drm/imx/imx-drm-core.c
@@ -288,8 +288,8 @@ static int imx_drm_bind(struct device *dev)
 err_unbind:
 #endif
 	component_unbind_all(drm->dev, drm);
-err_kms:
 	drm_mode_config_cleanup(drm);
+err_kms:
 	drm_dev_put(drm);
 
 	return ret;
@@ -313,9 +313,17 @@ static void imx_drm_unbind(struct device *dev)
 	drm_dev_put(drm);
 }
 
+static void imx_drm_cleanup(struct device *dev)
+{
+	struct drm_device *drm = dev_get_drvdata(dev);
+
+	drm_mode_config_cleanup(drm);
+}
+
 static const struct component_master_ops imx_drm_ops = {
 	.bind = imx_drm_bind,
 	.unbind = imx_drm_unbind,
+	.cleanup = imx_drm_cleanup,
 };
 
 static int imx_drm_platform_probe(struct platform_device *pdev)
-- 
2.19.1