tree: https://github.com/jgunthorpe/linux vfio_ccw head: d0d01fdc87368c19ee6cac8e7ab2c0ef7ab33efb commit: c7863bcc74538df3d39bd9407ae77f6ef778f7b3 [7/12] vfio/mdev: Add mdev available instance checking to the core config: x86_64-randconfig-m001-20210914 (attached as .config) compiler: gcc-9 (Debian 9.3.0-22) 9.3.0 If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; Reported-by: Dan Carpenter <dan.carpenter(a)oracle.com&gt; smatch warnings: drivers/vfio/mdev/mdev_core.c:319 mdev_device_create() warn: variable dereferenced before check 'drv' (see line 272) vim +/drv +319 drivers/vfio/mdev/mdev_core.c 417fd5bf242d76 Jason Gunthorpe 2021-04-06 255 int mdev_device_create(struct mdev_type *type, const guid_t *uuid) 7b96953bc640b6 Kirti Wankhede 2016-11-17 256 { 7b96953bc640b6 Kirti Wankhede 2016-11-17 257 int ret; 002fe996f67f4f Alex Williamson 2018-05-15 258 struct mdev_device *mdev, *tmp; a9f8111d0b5f44 Jason Gunthorpe 2021-04-06 259 struct mdev_parent *parent = type->parent; 88a21f265ce50a Jason Gunthorpe 2021-06-17 260 struct mdev_driver *drv = parent->ops->device_driver; 7b96953bc640b6 Kirti Wankhede 2016-11-17 261 002fe996f67f4f Alex Williamson 2018-05-15 262 mutex_lock(&mdev_list_lock); 7b96953bc640b6 Kirti Wankhede 2016-11-17 263 7b96953bc640b6 Kirti Wankhede 2016-11-17 264 /* Check for duplicate */ 002fe996f67f4f Alex Williamson 2018-05-15 265 list_for_each_entry(tmp, &mdev_list, next) { 278bca7f318e6a Andy Shevchenko 2019-01-10 266 if (guid_equal(&tmp->uuid, uuid)) { 002fe996f67f4f Alex Williamson 2018-05-15 267 mutex_unlock(&mdev_list_lock); fbd0e2b0c3d0b2 Jason Gunthorpe 2021-04-06 268 return -EEXIST; 002fe996f67f4f Alex Williamson 2018-05-15 269 } 7b96953bc640b6 Kirti Wankhede 2016-11-17 270 } 7b96953bc640b6 Kirti Wankhede 2016-11-17 271 c7863bcc74538d Jason Gunthorpe 2021-09-07 @272 if (drv->get_available) { ^^^^^^^^^^^^^^^^^^ Dereference c7863bcc74538d Jason Gunthorpe 2021-09-07 273 if (!type->available) { c7863bcc74538d Jason Gunthorpe 2021-09-07 274 mutex_unlock(&mdev_list_lock); c7863bcc74538d Jason Gunthorpe 2021-09-07 275 return -EUSERS; c7863bcc74538d Jason Gunthorpe 2021-09-07 276 } c7863bcc74538d Jason Gunthorpe 2021-09-07 277 type->available--; c7863bcc74538d Jason Gunthorpe 2021-09-07 278 } c7863bcc74538d Jason Gunthorpe 2021-09-07 279 7b96953bc640b6 Kirti Wankhede 2016-11-17 280 mdev = kzalloc(sizeof(*mdev), GFP_KERNEL); 7b96953bc640b6 Kirti Wankhede 2016-11-17 281 if (!mdev) { 002fe996f67f4f Alex Williamson 2018-05-15 282 mutex_unlock(&mdev_list_lock); fbd0e2b0c3d0b2 Jason Gunthorpe 2021-04-06 283 return -ENOMEM; 7b96953bc640b6 Kirti Wankhede 2016-11-17 284 } 7b96953bc640b6 Kirti Wankhede 2016-11-17 285 fbd0e2b0c3d0b2 Jason Gunthorpe 2021-04-06 286 device_initialize(&mdev->dev); fbd0e2b0c3d0b2 Jason Gunthorpe 2021-04-06 287 mdev->dev.parent = parent->dev; fbd0e2b0c3d0b2 Jason Gunthorpe 2021-04-06 288 mdev->dev.bus = &mdev_bus_type; fbd0e2b0c3d0b2 Jason Gunthorpe 2021-04-06 289 mdev->dev.release = mdev_device_release; fbd0e2b0c3d0b2 Jason Gunthorpe 2021-04-06 290 mdev->dev.groups = parent->ops->mdev_attr_groups; fbd0e2b0c3d0b2 Jason Gunthorpe 2021-04-06 291 mdev->type = type; fbd0e2b0c3d0b2 Jason Gunthorpe 2021-04-06 292 /* Pairs with the put in mdev_device_release() */ fbea43239074e1 Jason Gunthorpe 2021-04-06 293 kobject_get(&type->kobj); fbd0e2b0c3d0b2 Jason Gunthorpe 2021-04-06 294 278bca7f318e6a Andy Shevchenko 2019-01-10 295 guid_copy(&mdev->uuid, uuid); 002fe996f67f4f Alex Williamson 2018-05-15 296 list_add(&mdev->next, &mdev_list); 002fe996f67f4f Alex Williamson 2018-05-15 297 mutex_unlock(&mdev_list_lock); 002fe996f67f4f Alex Williamson 2018-05-15 298 18d731242d5c67 Jason Gunthorpe 2021-04-06 299 ret = dev_set_name(&mdev->dev, "%pUl", uuid); 18d731242d5c67 Jason Gunthorpe 2021-04-06 300 if (ret) 18d731242d5c67 Jason Gunthorpe 2021-04-06 301 goto out_put_device; 7b96953bc640b6 Kirti Wankhede 2016-11-17 302 5715c4dd66a315 Parav Pandit 2019-06-06 303 /* Check if parent unregistration has started */ 5715c4dd66a315 Parav Pandit 2019-06-06 304 if (!down_read_trylock(&parent->unreg_sem)) { 5715c4dd66a315 Parav Pandit 2019-06-06 305 ret = -ENODEV; fbd0e2b0c3d0b2 Jason Gunthorpe 2021-04-06 306 goto out_put_device; 5715c4dd66a315 Parav Pandit 2019-06-06 307 } 5715c4dd66a315 Parav Pandit 2019-06-06 308 88a21f265ce50a Jason Gunthorpe 2021-06-17 309 if (parent->ops->create) { c2ef2f50ad0ccf Jason Gunthorpe 2021-04-06 310 ret = parent->ops->create(mdev); 522ecce08ab20b Parav Pandit 2019-06-06 311 if (ret) fbd0e2b0c3d0b2 Jason Gunthorpe 2021-04-06 312 goto out_unlock; 88a21f265ce50a Jason Gunthorpe 2021-06-17 313 } 7b96953bc640b6 Kirti Wankhede 2016-11-17 314 522ecce08ab20b Parav Pandit 2019-06-06 315 ret = device_add(&mdev->dev); 7b96953bc640b6 Kirti Wankhede 2016-11-17 316 if (ret) fbd0e2b0c3d0b2 Jason Gunthorpe 2021-04-06 317 goto out_remove; 7b96953bc640b6 Kirti Wankhede 2016-11-17 318 88a21f265ce50a Jason Gunthorpe 2021-06-17 @319 if (!drv) ^^^^ Check for NULL too late. Probably move it forward. 88a21f265ce50a Jason Gunthorpe 2021-06-17 320 drv = &vfio_mdev_driver; 88a21f265ce50a Jason Gunthorpe 2021-06-17 321 ret = device_driver_attach(&drv->driver, &mdev->dev); 88a21f265ce50a Jason Gunthorpe 2021-06-17 322 if (ret) 88a21f265ce50a Jason Gunthorpe 2021-06-17 323 goto out_del; 88a21f265ce50a Jason Gunthorpe 2021-06-17 324 417fd5bf242d76 Jason Gunthorpe 2021-04-06 325 ret = mdev_create_sysfs_files(mdev); 522ecce08ab20b Parav Pandit 2019-06-06 326 if (ret) fbd0e2b0c3d0b2 Jason Gunthorpe 2021-04-06 327 goto out_del; 7b96953bc640b6 Kirti Wankhede 2016-11-17 328 002fe996f67f4f Alex Williamson 2018-05-15 329 mdev->active = true; 7b96953bc640b6 Kirti Wankhede 2016-11-17 330 dev_dbg(&mdev->dev, "MDEV: created\n"); 5715c4dd66a315 Parav Pandit 2019-06-06 331 up_read(&parent->unreg_sem); 7b96953bc640b6 Kirti Wankhede 2016-11-17 332 002fe996f67f4f Alex Williamson 2018-05-15 333 return 0; 7b96953bc640b6 Kirti Wankhede 2016-11-17 334 fbd0e2b0c3d0b2 Jason Gunthorpe 2021-04-06 335 out_del: 522ecce08ab20b Parav Pandit 2019-06-06 336 device_del(&mdev->dev); fbd0e2b0c3d0b2 Jason Gunthorpe 2021-04-06 337 out_remove: 88a21f265ce50a Jason Gunthorpe 2021-06-17 338 if (parent->ops->remove) 522ecce08ab20b Parav Pandit 2019-06-06 339 parent->ops->remove(mdev); fbd0e2b0c3d0b2 Jason Gunthorpe 2021-04-06 340 out_unlock: 5715c4dd66a315 Parav Pandit 2019-06-06 341 up_read(&parent->unreg_sem); fbd0e2b0c3d0b2 Jason Gunthorpe 2021-04-06 342 out_put_device: 522ecce08ab20b Parav Pandit 2019-06-06 343 put_device(&mdev->dev); 7b96953bc640b6 Kirti Wankhede 2016-11-17 344 return ret; 7b96953bc640b6 Kirti Wankhede 2016-11-17 345 } --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org