From: Yang Yingliang yangyingliang@huawei.com
[ Upstream commit 1f386d6894d0f1b7de8ef640c41622ddd698e7ab ]
I got a UAF report as following:
================================================================== BUG: KASAN: use-after-free in __lock_acquire+0x935/0x2060 Read of size 8 at addr ffff88810e838220 by task python3/268 Call Trace: <TASK> dump_stack_lvl+0x67/0x83 print_report+0x178/0x4b0 kasan_report+0x90/0x190 __lock_acquire+0x935/0x2060 lock_acquire+0x156/0x400 _raw_spin_lock+0x2a/0x40 lockref_get+0x11/0x30 simple_recursive_removal+0x41/0x440 debugfs_remove.part.12+0x32/0x50 debugfs_remove+0x29/0x30 _regulator_put.cold.54+0x3e/0x27f regulator_put+0x1f/0x30 release_nodes+0x6a/0xa0 devres_release_all+0xf8/0x150
Allocated by task 37: kasan_save_stack+0x1c/0x40 kasan_set_track+0x21/0x30 __kasan_slab_alloc+0x5d/0x70 slab_post_alloc_hook+0x62/0x510 kmem_cache_alloc_lru+0x222/0x5a0 __d_alloc+0x31/0x440 d_alloc+0x30/0xf0 d_alloc_parallel+0xc4/0xd20 __lookup_slow+0x15e/0x2f0 lookup_one_len+0x13a/0x150 start_creating+0xea/0x190 debugfs_create_dir+0x1e/0x210 create_regulator+0x254/0x4e0 _regulator_get+0x2a1/0x467 _devm_regulator_get+0x5a/0xb0 regulator_virtual_probe+0xb9/0x1a0
Freed by task 30: kasan_save_stack+0x1c/0x40 kasan_set_track+0x21/0x30 kasan_save_free_info+0x2a/0x50 __kasan_slab_free+0x102/0x190 kmem_cache_free+0xf6/0x600 rcu_core+0x54c/0x12b0 __do_softirq+0xf2/0x5e3
Last potentially related work creation: kasan_save_stack+0x1c/0x40 __kasan_record_aux_stack+0x98/0xb0 call_rcu+0x42/0x700 dentry_free+0x6c/0xd0 __dentry_kill+0x23b/0x2d0 dput.part.31+0x431/0x780 simple_recursive_removal+0xa9/0x440 debugfs_remove.part.12+0x32/0x50 debugfs_remove+0x29/0x30 regulator_unregister+0xe3/0x230 release_nodes+0x6a/0xa0
==================================================================
Here is how happened:
processor A processor B regulator_register() rdev_init_debugfs() rdev->debugfs = debugfs_create_dir() devm_regulator_get() rdev = regulator_dev_lookup() create_regulator(rdev) // using rdev->debugfs as parent debugfs_create_dir(rdev->debugfs)
mfd_remove_devices_fn() release_nodes() regulator_unregister() // free rdev->debugfs debugfs_remove_recursive(rdev->debugfs) release_nodes() destroy_regulator() debugfs_remove_recursive() <- causes UAF
In devm_regulator_get(), after getting rdev, the refcount is get, so fix this by moving debugfs_remove_recursive() to regulator_dev_release(), then it can be proctected by the refcount, the 'rdev->debugfs' can not be freed until the refcount is 0.
Fixes: 5de705194e98 ("regulator: Add basic per consumer debugfs") Signed-off-by: Yang Yingliang yangyingliang@huawei.com Link: https://lore.kernel.org/r/20221116033706.3595812-1-yangyingliang@huawei.com Signed-off-by: Mark Brown broonie@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/regulator/core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c index 173798c0fbcd..7d15312d6792 100644 --- a/drivers/regulator/core.c +++ b/drivers/regulator/core.c @@ -4802,6 +4802,7 @@ static void regulator_dev_release(struct device *dev) { struct regulator_dev *rdev = dev_get_drvdata(dev);
+ debugfs_remove_recursive(rdev->debugfs); kfree(rdev->constraints); of_node_put(rdev->dev.of_node); kfree(rdev); @@ -5306,7 +5307,6 @@ void regulator_unregister(struct regulator_dev *rdev)
mutex_lock(®ulator_list_mutex);
- debugfs_remove_recursive(rdev->debugfs); WARN_ON(rdev->open_count); regulator_remove_coupling(rdev); unset_regulator_supplies(rdev);