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1f386d6894
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>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.