linux-kernel - [PATCH 5.15 042/135] drm/sun4i: Fix crash during suspend after component bind failure

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Date:   Mon, 27 Jun 2022 13:20:49 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Samuel Holland <samuel@...lland.org>,
        Jernej Skrabec <jernej.skrabec@...il.com>,
        Maxime Ripard <maxime@...no.tech>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.15 042/135] drm/sun4i: Fix crash during suspend after component bind failure

From: Samuel Holland <samuel@...lland.org>

[ Upstream commit 1342b5b23da9559a1578978eaff7f797d8a87d91 ]

If the component driver fails to bind, or is unbound, the driver data
for the top-level platform device points to a freed drm_device. If the
system is then suspended, the driver passes this dangling pointer to
drm_mode_config_helper_suspend(), which crashes.

Fix this by only setting the driver data while the platform driver holds
a reference to the drm_device.

Fixes: 624b4b48d9d8 ("drm: sun4i: Add support for suspending the display driver")
Signed-off-by: Samuel Holland <samuel@...lland.org>
Reviewed-by: Jernej Skrabec <jernej.skrabec@...il.com>
Signed-off-by: Maxime Ripard <maxime@...no.tech>
Link: https://lore.kernel.org/r/20220615054254.16352-1-samuel@sholland.org
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/gpu/drm/sun4i/sun4i_drv.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/sun4i/sun4i_drv.c b/drivers/gpu/drm/sun4i/sun4i_drv.c
index 54dd562e294c..5b7061e2bca4 100644
--- a/drivers/gpu/drm/sun4i/sun4i_drv.c
+++ b/drivers/gpu/drm/sun4i/sun4i_drv.c
@@ -72,7 +72,6 @@ static int sun4i_drv_bind(struct device *dev)
 		goto free_drm;
 	}
 
-	dev_set_drvdata(dev, drm);
 	drm->dev_private = drv;
 	INIT_LIST_HEAD(&drv->frontend_list);
 	INIT_LIST_HEAD(&drv->engine_list);
@@ -113,6 +112,8 @@ static int sun4i_drv_bind(struct device *dev)
 
 	drm_fbdev_generic_setup(drm, 32);
 
+	dev_set_drvdata(dev, drm);
+
 	return 0;
 
 finish_poll:
@@ -129,6 +130,7 @@ static void sun4i_drv_unbind(struct device *dev)
 {
 	struct drm_device *drm = dev_get_drvdata(dev);
 
+	dev_set_drvdata(dev, NULL);
 	drm_dev_unregister(drm);
 	drm_kms_helper_poll_fini(drm);
 	drm_atomic_helper_shutdown(drm);
-- 
2.35.1