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author | ChenXiaoSong <chenxiaosong2@huawei.com> | 2022-02-15 15:10:30 +0800 |
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committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-03-02 11:38:13 +0100 |
commit | a37024f7757c25550accdebf49e497ad6ae239fe (patch) | |
tree | e9b85ed16b591225ced80328d84ad9ac197c3847 /fs/dlm | |
parent | 0921d16eb7daadcba871889003fac494f6efc0f5 (diff) | |
download | linux-stable-a37024f7757c25550accdebf49e497ad6ae239fe.tar.gz linux-stable-a37024f7757c25550accdebf49e497ad6ae239fe.tar.bz2 linux-stable-a37024f7757c25550accdebf49e497ad6ae239fe.zip |
configfs: fix a race in configfs_{,un}register_subsystem()
[ Upstream commit 84ec758fb2daa236026506868c8796b0500c047d ]
When configfs_register_subsystem() or configfs_unregister_subsystem()
is executing link_group() or unlink_group(),
it is possible that two processes add or delete list concurrently.
Some unfortunate interleavings of them can cause kernel panic.
One of cases is:
A --> B --> C --> D
A <-- B <-- C <-- D
delete list_head *B | delete list_head *C
--------------------------------|-----------------------------------
configfs_unregister_subsystem | configfs_unregister_subsystem
unlink_group | unlink_group
unlink_obj | unlink_obj
list_del_init | list_del_init
__list_del_entry | __list_del_entry
__list_del | __list_del
// next == C |
next->prev = prev |
| next->prev = prev
prev->next = next |
| // prev == B
| prev->next = next
Fix this by adding mutex when calling link_group() or unlink_group(),
but parent configfs_subsystem is NULL when config_item is root.
So I create a mutex configfs_subsystem_mutex.
Fixes: 7063fbf22611 ("[PATCH] configfs: User-driven configuration filesystem")
Signed-off-by: ChenXiaoSong <chenxiaosong2@huawei.com>
Signed-off-by: Laibin Qiu <qiulaibin@huawei.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'fs/dlm')
0 files changed, 0 insertions, 0 deletions