From: Ziyang Xuan william.xuanziyang@huawei.com
commit 0a5c26712f963f0500161a23e0ffff8d29f742ab upstream.
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.... Signed-off-by: Daniel Lezcano daniel.lezcano@linaro.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/thermal/thermal_core.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
--- a/drivers/thermal/thermal_core.c +++ b/drivers/thermal/thermal_core.c @@ -1092,7 +1092,7 @@ __thermal_cooling_device_register(struct { struct thermal_cooling_device *cdev; struct thermal_zone_device *pos = NULL; - int ret; + int id, ret;
if (!ops || !ops->get_max_state || !ops->get_cur_state || !ops->set_cur_state) @@ -1106,6 +1106,7 @@ __thermal_cooling_device_register(struct if (ret < 0) goto out_kfree_cdev; cdev->id = ret; + id = ret;
cdev->type = kstrdup(type ? type : "", GFP_KERNEL); if (!cdev->type) { @@ -1147,8 +1148,9 @@ out_kfree_type: thermal_cooling_device_destroy_sysfs(cdev); kfree(cdev->type); put_device(&cdev->device); + cdev = NULL; out_ida_remove: - ida_simple_remove(&thermal_cdev_ida, cdev->id); + ida_simple_remove(&thermal_cdev_ida, id); out_kfree_cdev: return ERR_PTR(ret); }