[PATCH 5.15 435/917] thermal/core: fix a UAF bug in __thermal_cooling_device_register()

Greg Kroah-Hartman
2021-11-16T00:40:12Z

From: Ziyang Xuan <william.xuanziyang@huawei.com>

[ Upstream commit 0a5c26712f963f0500161a23e0ffff8d29f742ab ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/thermal/thermal_core.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
index d094ebbde0ed7..30134f49b037a 100644
--- a/drivers/thermal/thermal_core.c
+++ b/drivers/thermal/thermal_core.c
@@ -887,7 +887,7 @@ __thermal_cooling_device_register(struct device_node *np,
{
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)
@@ -901,6 +901,7 @@ __thermal_cooling_device_register(struct device_node *np,
if (ret < 0)
goto out_kfree_cdev;
cdev->id = ret;
+ id = ret;

ret = dev_set_name(&cdev->device, "cooling_device%d", cdev->id);
if (ret)
@@ -944,8 +945,9 @@ __thermal_cooling_device_register(struct device_node *np,
out_kfree_type:
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:
kfree(cdev);
return ERR_PTR(ret);
--
2.33.0