Re: [PATCH] thermal/core: fix a UAF bug in __thermal_cooling_device_register()

[kernel test robot]

Hi Ziyang,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on rafael-pm/thermal]
[also build test WARNING on v5.15-rc5 next-20211013]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Ziyang-Xuan/thermal-core-fix-a-UAF-bug-in-__thermal_cooling_device_register/20211014-164859
base:   https://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git thermal
config: hexagon-randconfig-r005-20211014 (attached as .config)
compiler: clang version 14.0.0 (https://github.com/llvm/llvm-project 6c76d0101193aa4eb891a6954ff047eda2f9cf71)
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/0day-ci/linux/commit/fb39770678d4d898891ede9121c811844b5f2890
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Ziyang-Xuan/thermal-core-fix-a-UAF-bug-in-__thermal_cooling_device_register/20211014-164859
        git checkout fb39770678d4d898891ede9121c811844b5f2890
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 ARCH=hexagon 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@xxxxxxxxx>

All warnings (new ones prefixed by >>):

>> drivers/thermal/thermal_core.c:901:6: warning: variable 'ret' is used uninitialized whenever 'if' condition is true [-Wsometimes-uninitialized]
           if (id < 0)
               ^~~~~~
   drivers/thermal/thermal_core.c:949:17: note: uninitialized use occurs here
           return ERR_PTR(ret);
                          ^~~
   drivers/thermal/thermal_core.c:901:2: note: remove the 'if' if its condition is always false
           if (id < 0)
           ^~~~~~~~~~~
   drivers/thermal/thermal_core.c:890:13: note: initialize the variable 'ret' to silence this warning
           int id, ret;
                      ^
                       = 0
   1 warning generated.


vim +901 drivers/thermal/thermal_core.c

   866	
   867	/**
   868	 * __thermal_cooling_device_register() - register a new thermal cooling device
   869	 * @np:		a pointer to a device tree node.
   870	 * @type:	the thermal cooling device type.
   871	 * @devdata:	device private data.
   872	 * @ops:		standard thermal cooling devices callbacks.
   873	 *
   874	 * This interface function adds a new thermal cooling device (fan/processor/...)
   875	 * to /sys/class/thermal/ folder as cooling_device[0-*]. It tries to bind itself
   876	 * to all the thermal zone devices registered at the same time.
   877	 * It also gives the opportunity to link the cooling device to a device tree
   878	 * node, so that it can be bound to a thermal zone created out of device tree.
   879	 *
   880	 * Return: a pointer to the created struct thermal_cooling_device or an
   881	 * ERR_PTR. Caller must check return value with IS_ERR*() helpers.
   882	 */
   883	static struct thermal_cooling_device *
   884	__thermal_cooling_device_register(struct device_node *np,
   885					  const char *type, void *devdata,
   886					  const struct thermal_cooling_device_ops *ops)
   887	{
   888		struct thermal_cooling_device *cdev;
   889		struct thermal_zone_device *pos = NULL;
   890		int id, ret;
   891	
   892		if (!ops || !ops->get_max_state || !ops->get_cur_state ||
   893		    !ops->set_cur_state)
   894			return ERR_PTR(-EINVAL);
   895	
   896		cdev = kzalloc(sizeof(*cdev), GFP_KERNEL);
   897		if (!cdev)
   898			return ERR_PTR(-ENOMEM);
   899	
   900		id = ida_simple_get(&thermal_cdev_ida, 0, 0, GFP_KERNEL);
 > 901		if (id < 0)
   902			goto out_kfree_cdev;
   903		cdev->id = id;
   904	
   905		cdev->type = kstrdup(type ? type : "", GFP_KERNEL);
   906		if (!cdev->type) {
   907			ret = -ENOMEM;
   908			goto out_ida_remove;
   909		}
   910	
   911		mutex_init(&cdev->lock);
   912		INIT_LIST_HEAD(&cdev->thermal_instances);
   913		cdev->np = np;
   914		cdev->ops = ops;
   915		cdev->updated = false;
   916		cdev->device.class = &thermal_class;
   917		cdev->devdata = devdata;
   918		thermal_cooling_device_setup_sysfs(cdev);
   919		dev_set_name(&cdev->device, "cooling_device%d", cdev->id);
   920		ret = device_register(&cdev->device);
   921		if (ret)
   922			goto out_kfree_type;
   923	
   924		/* Add 'this' new cdev to the global cdev list */
   925		mutex_lock(&thermal_list_lock);
   926		list_add(&cdev->node, &thermal_cdev_list);
   927		mutex_unlock(&thermal_list_lock);
   928	
   929		/* Update binding information for 'this' new cdev */
   930		bind_cdev(cdev);
   931	
   932		mutex_lock(&thermal_list_lock);
   933		list_for_each_entry(pos, &thermal_tz_list, node)
   934			if (atomic_cmpxchg(&pos->need_update, 1, 0))
   935				thermal_zone_device_update(pos,
   936							   THERMAL_EVENT_UNSPECIFIED);
   937		mutex_unlock(&thermal_list_lock);
   938	
   939		return cdev;
   940	
   941	out_kfree_type:
   942		kfree(cdev->type);
   943		put_device(&cdev->device);
   944		cdev = NULL;
   945	out_ida_remove:
   946		ida_simple_remove(&thermal_cdev_ida, id);
   947	out_kfree_cdev:
   948		kfree(cdev);
   949		return ERR_PTR(ret);
   950	}
   951	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@xxxxxxxxxxxx

Attachment: .config.gz
Description: application/gzip