ChenXiaoSong a7ab53d3c2 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: 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 11:42:52 +01:00
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configfs_internal.h
dir.c	configfs: fix a race in configfs_{,un}register_subsystem()	2022-03-02 11:42:52 +01:00
file.c
inode.c
item.c
Kconfig
Makefile
mount.c
symlink.c