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Commit 1626fc29 authored by Krishna Manikandan's avatar Krishna Manikandan Committed by Alexander Grund
Browse files

disp: msm: sde: add null check for drm file in msm_release 

Drm file is not set to NULL after freeing it from drm
release. This can result in use-after-free issues in
some scenarios. Add a mutex lock and other proper null
checks to prevent such issues.

Change-Id: Ic35b0a76166b0f47a354b1737e6f4c3ac1437ed4
parent f2ee0b1f

drivers/gpu/drm/msm/msm_drv.c

+22 −5
Original line number Diff line number Diff line 
/*

 * Copyright (c) 2016-2019, The Linux Foundation. All rights reserved.

 * Copyright (c) 2016-2021, The Linux Foundation. All rights reserved.

 * Copyright (C) 2013 Red Hat

 * Author: Rob Clark <robdclark@gmail.com>

 *
@@ -97,6 +97,8 @@ static void msm_drm_helper_hotplug_event(struct drm_device *dev) 
	kfree(event_string);

}



static DEFINE_MUTEX(msm_release_lock);



static void msm_fb_output_poll_changed(struct drm_device *dev)

{

	struct msm_drm_private *priv = NULL;
@@ -1850,11 +1852,22 @@ static int msm_ioctl_submitqueue_close(struct drm_device *dev, void *data, 
int msm_release(struct inode *inode, struct file *filp)

{

	struct drm_file *file_priv = filp->private_data;

	struct drm_minor *minor = file_priv->minor;

	struct drm_device *dev = minor->dev;

	struct msm_drm_private *priv = dev->dev_private;

	struct drm_minor *minor;

	struct drm_device *dev;

	struct msm_drm_private *priv;

	struct msm_drm_event *v, *vt;

	unsigned long flags;

	int ret = 0;



	mutex_lock(&msm_release_lock);



	if (!file_priv) {

		ret = -EINVAL;

		goto end;

	}

	minor = file_priv->minor;

	dev = minor->dev;

	priv = dev->dev_private;



	spin_lock_irqsave(&dev->event_lock, flags);

	list_for_each_entry_safe(v, vt, &priv->client_event_list, base.link) {
@@ -1866,7 +1879,11 @@ int msm_release(struct inode *inode, struct file *filp) 
	}

	spin_unlock_irqrestore(&dev->event_lock, flags);



	return drm_release(inode, filp);

	ret = drm_release(inode, filp);

	filp->private_data = NULL;

end:

	mutex_unlock(&msm_release_lock);

	return ret;

}



/**