thermal/core: fix a UAF bug in __thermal_cooling_device_register()

When device_register() return failed, program will goto out_kfree_type
to release 'cdev->device' by put_device(). That will call thermal_release()
to free 'cdev'. But the follow-up processes access 'cdev' continually.
That trggers the UAF bug.

====================================================================
BUG: KASAN: use-after-free in __thermal_cooling_device_register+0x75b/0xa90
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014
Call Trace:
 dump_stack_lvl+0xe2/0x152
 print_address_description.constprop.0+0x21/0x140
 ? __thermal_cooling_device_register+0x75b/0xa90
 kasan_report.cold+0x7f/0x11b
 ? __thermal_cooling_device_register+0x75b/0xa90
 __thermal_cooling_device_register+0x75b/0xa90
 ? memset+0x20/0x40
 ? __sanitizer_cov_trace_pc+0x1d/0x50
 ? __devres_alloc_node+0x130/0x180
 devm_thermal_of_cooling_device_register+0x67/0xf0
 max6650_probe.cold+0x557/0x6aa
......

Freed by task 258:
 kasan_save_stack+0x1b/0x40
 kasan_set_track+0x1c/0x30
 kasan_set_free_info+0x20/0x30
 __kasan_slab_free+0x109/0x140
 kfree+0x117/0x4c0
 thermal_release+0xa0/0x110
 device_release+0xa7/0x240
 kobject_put+0x1ce/0x540
 put_device+0x20/0x30
 __thermal_cooling_device_register+0x731/0xa90
 devm_thermal_of_cooling_device_register+0x67/0xf0
 max6650_probe.cold+0x557/0x6aa [max6650]

Do not use 'cdev' again after put_device() to fix the problem like doing
in thermal_zone_device_register().

[dlezcano]: as requested by Rafael, change the affectation into two statements.

Fixes: 584837618100 ("thermal/drivers/core: Use a char pointer for the cooling device name")
Signed-off-by: Ziyang Xuan <william.xuanziyang@huawei.com>
Reported-by: kernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/r/20211015024504.947520-1-william.xuanziyang@huawei.com
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>

0 files changed, 0 insertions, 0 deletions