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From: oushixiong <oushixiong@kylinos.cn>
To: Xinliang Liu <xinliang.liu@linaro.org>
Cc: Tian Tao <tiantao6@hisilicon.com>,
	Xinwei Kong <kong.kongxinwei@hisilicon.com>,
	Sumit Semwal <sumit.semwal@linaro.org>,
	Yongqin Liu <yongqin.liu@linaro.org>,
	John Stultz <jstultz@google.com>,
	Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
	Maxime Ripard <mripard@kernel.org>,
	Thomas Zimmermann <tzimmermann@suse.de>,
	David Airlie <airlied@gmail.com>,
	Daniel Vetter <daniel@ffwll.ch>,
	dri-devel@lists.freedesktop.org,
	linux-kernel@vger.kernel.org,
	Shixiong Ou <oushixiong@kylinos.cn>
Subject: [PATCH] drm/hisilicon: Fix a NULL pointer access when call hibmc_unload
Date: Thu,  9 May 2024 17:05:01 +0800
Message-Id: <20240509090501.127975-1-oushixiong@kylinos.cn>
Precedence: bulk
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From: Shixiong Ou <oushixiong@kylinos.cn>

If Calling hibmc_mm_init() failed in hibmc_load(), the hibmc_unload()
will access a NULL pointer, as it don't call ww_mutex_init() to
initialize mode_config.connection_mutex but try to lock it when
calling drm_atomic_helper_shutdown().

[   50.939211][  0] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000018
	......
[   51.149882][  0] Call trace:
[   51.152750][  0]  ww_mutex_lock+0xf0/0x1e0
[   51.156829][  0]  drm_modeset_lock+0x184/0x2c0
[   51.161254][  0]  drm_modeset_lock_all_ctx+0x98/0x188
[   51.166284][  0]  drm_atomic_helper_shutdown+0xa4/0x128
[   51.171487][  0]  hibmc_unload+0x50/0x2f0
[   51.175479][  0]  hibmc_load+0x5d8/0x888
[   51.179386][  0]  drm_dev_register+0x280/0x558
[   51.183811][  0]  drm_get_pci_dev+0x140/0x3c8
[   51.188150][  0]  hibmc_pci_probe+0x148/0x190
[   51.192489][  0]  local_pci_probe+0xc4/0x180
[   51.196742][  0]  pci_device_probe+0x328/0x530
[   51.201167][  0]  really_probe+0x498/0x9a0
[   51.205248][  0]  driver_probe_device+0x224/0x308
[   51.209932][  0]  device_driver_attach+0xec/0x128
[   51.214616][  0]  __driver_attach+0x144/0x280
[   51.218955][  0]  bus_for_each_dev+0x120/0x1a0
[   51.223380][  0]  driver_attach+0x48/0x60
[   51.227372][  0]  bus_add_driver+0x328/0x578
[   51.231625][  0]  driver_register+0x148/0x398
[   51.235965][  0]  __pci_register_driver+0x15c/0x1c8
[   51.240823][  0]  hibmc_init+0x2c/0x34
[   51.244557][  0]  do_one_initcall+0xc8/0x4a8
[   51.248810][  0]  kernel_init_freeable+0x678/0x75c
[   51.253582][  0]  kernel_init+0x18/0x128
[   51.257489][  0]  ret_from_fork+0x10/0x18

Add a initialized flag to avoid this.

Signed-off-by: Shixiong Ou <oushixiong@kylinos.cn>
---
 drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c | 8 ++++++--
 drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.h | 1 +
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c
index 57c21ec452b7..343f64d66e75 100644
--- a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c
+++ b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c
@@ -99,6 +99,7 @@ static int hibmc_kms_init(struct hibmc_drm_private *priv)
 	ret = drmm_mode_config_init(dev);
 	if (ret)
 		return ret;
+	priv->mode_config_initialized = true;
 
 	dev->mode_config.min_width = 0;
 	dev->mode_config.min_height = 0;
@@ -240,9 +241,12 @@ static int hibmc_hw_init(struct hibmc_drm_private *priv)
 static int hibmc_unload(struct drm_device *dev)
 {
 	struct pci_dev *pdev = to_pci_dev(dev->dev);
+	struct hibmc_drm_private *priv = to_hibmc_drm_private(dev);
 
-	drm_atomic_helper_shutdown(dev);
-
+	if(priv->mode_config_initialized){
+		drm_atomic_helper_shutdown(dev);
+		priv->mode_config_initialized = false;
+	}
 	free_irq(pdev->irq, dev);
 
 	pci_disable_msi(to_pci_dev(dev->dev));
diff --git a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.h b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.h
index 207aa3f660b0..08fd7cb59bb5 100644
--- a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.h
+++ b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.h
@@ -37,6 +37,7 @@ struct hibmc_drm_private {
 	struct drm_crtc crtc;
 	struct drm_encoder encoder;
 	struct hibmc_connector connector;
+	bool mode_config_initialized;
 };
 
 static inline struct hibmc_connector *to_hibmc_connector(struct drm_connector *connector)
-- 
2.25.1