ChenXiaoSong e7a66dd268 configfs: fix a race in configfs_{,un}register_subsystem() ... [ Upstream commit 84ec758fb2 ] 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: 7063fbf226 ("[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>		2022-03-02 11:48:02 +01:00
..
Kconfig	treewide: Add SPDX license identifier - Makefile/Kconfig	2019-05-21 10:50:46 +02:00
Makefile	treewide: Add SPDX license identifier - Makefile/Kconfig	2019-05-21 10:50:46 +02:00
configfs_internal.h	treewide: remove editor modelines and cruft	2021-05-07 00:26:34 -07:00
dir.c	configfs: fix a race in configfs_{,un}register_subsystem()	2022-03-02 11:48:02 +01:00
file.c	configfs: restore the kernel v5.13 text attribute write behavior	2021-08-09 16:56:00 +02:00
inode.c	fs: move ramfs_aops to libfs	2021-06-29 10:53:48 -07:00
item.c	treewide: remove editor modelines and cruft	2021-05-07 00:26:34 -07:00
mount.c	treewide: remove editor modelines and cruft	2021-05-07 00:26:34 -07:00
symlink.c	treewide: remove editor modelines and cruft	2021-05-07 00:26:34 -07:00