[Intel-gfx] [PATCH 03/51] drm: add managed resources tied to drm_device

[Daniel Vetter]

On Tue, Mar 03, 2020 at 11:04:06AM +0300, Dan Carpenter wrote:
> Hi Daniel,
> 
> I love your patch! Perhaps something to improve:
> 
> url:    https://github.com/0day-ci/linux/commits/Daniel-Vetter/drm_device-managed-resources-v4/20200303-071023
> base:   git://anongit.freedesktop.org/drm/drm-tip drm-tip
> 
> If you fix the issue, kindly add following tag
> Reported-by: kbuild test robot <lkp at intel.com>
> Reported-by: Dan Carpenter <dan.carpenter at oracle.com>
> 
> smatch warnings:
> drivers/gpu/drm/drm_drv.c:843 drm_dev_release() error: dereferencing freed memory 'dev'
> 
> # https://github.com/0day-ci/linux/commit/5aba700d4c32ae5722a9931c959b13a6217a86e2
> git remote add linux-review https://github.com/0day-ci/linux
> git remote update linux-review
> git checkout 5aba700d4c32ae5722a9931c959b13a6217a86e2
> vim +/dev +843 drivers/gpu/drm/drm_drv.c
> 
> 099d1c290e2ebc drivers/gpu/drm/drm_stub.c David Herrmann 2014-01-29  826  static void drm_dev_release(struct kref *ref)
> 0dc8fe5985e01f drivers/gpu/drm/drm_stub.c David Herrmann 2013-10-02  827  {
> 099d1c290e2ebc drivers/gpu/drm/drm_stub.c David Herrmann 2014-01-29  828  	struct drm_device *dev = container_of(ref, struct drm_device, ref);
> 8f6599da8e772f drivers/gpu/drm/drm_stub.c David Herrmann 2013-10-20  829  
> f30c92576af4bb drivers/gpu/drm/drm_drv.c  Chris Wilson   2017-02-02  830  	if (dev->driver->release) {
> f30c92576af4bb drivers/gpu/drm/drm_drv.c  Chris Wilson   2017-02-02  831  		dev->driver->release(dev);
> f30c92576af4bb drivers/gpu/drm/drm_drv.c  Chris Wilson   2017-02-02  832  	} else {
> f30c92576af4bb drivers/gpu/drm/drm_drv.c  Chris Wilson   2017-02-02  833  		drm_dev_fini(dev);
> 5aba700d4c32ae drivers/gpu/drm/drm_drv.c  Daniel Vetter  2020-03-02  834  	}
> 5aba700d4c32ae drivers/gpu/drm/drm_drv.c  Daniel Vetter  2020-03-02  835  
> 5aba700d4c32ae drivers/gpu/drm/drm_drv.c  Daniel Vetter  2020-03-02  836  	drm_managed_release(dev);
> 5aba700d4c32ae drivers/gpu/drm/drm_drv.c  Daniel Vetter  2020-03-02  837  
> 5aba700d4c32ae drivers/gpu/drm/drm_drv.c  Daniel Vetter  2020-03-02  838  	if (!dev->driver->release && !dev->managed.final_kfree) {
> 5aba700d4c32ae drivers/gpu/drm/drm_drv.c  Daniel Vetter  2020-03-02  839  		WARN_ON(!list_empty(&dev->managed.resources));
> 0dc8fe5985e01f drivers/gpu/drm/drm_stub.c David Herrmann 2013-10-02  840  		kfree(dev);
>                                                                                         ^^^^^^^^^^
> Free
> 
> 0dc8fe5985e01f drivers/gpu/drm/drm_stub.c David Herrmann 2013-10-02  841  	}
> 5aba700d4c32ae drivers/gpu/drm/drm_drv.c  Daniel Vetter  2020-03-02  842  
> 5aba700d4c32ae drivers/gpu/drm/drm_drv.c  Daniel Vetter  2020-03-02 @843  	if (dev->managed.final_kfree)
>                                                                                     ^^^^^
> Dereference

Drat, so much for me trying to get this to bisect properly (it's interim
code and will disappear, end is correct I  think). I guess I'll try again.
-Daniel

> 
> 5aba700d4c32ae drivers/gpu/drm/drm_drv.c  Daniel Vetter  2020-03-02  844  		kfree(dev->managed.final_kfree);
> f30c92576af4bb drivers/gpu/drm/drm_drv.c  Chris Wilson   2017-02-02  845  }
> 
> ---
> 0-DAY CI Kernel Test Service, Intel Corporation
> https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch