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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
arch KVM: x86/mmu: make apf token non-zero to fix bug 2022-03-02 11:47:49 +01:00
block block: fix surprise removal for drivers calling blk_set_queue_dying 2022-02-23 12:03:15 +01:00
certs certs: Add support for using elliptic curve keys for signing modules 2021-08-23 19:55:42 +03:00
crypto crypto: api - Move cryptomgr soft dependency into algapi 2022-02-11 09:10:26 +01:00
Documentation ARM: dts: Fix timer regression for beagleboard revision c 2022-02-16 12:56:21 +01:00
drivers bnxt_en: Increase firmware message response DMA wait time 2022-03-02 11:48:02 +01:00
fs configfs: fix a race in configfs_{,un}register_subsystem() 2022-03-02 11:48:02 +01:00
include net-timestamp: convert sk->sk_tskey to atomic_t 2022-03-02 11:48:01 +01:00
init init: make unknown command line param message clearer 2021-11-18 19:17:11 +01:00
ipc ipc/sem: do not sleep with a spin lock held 2022-02-08 18:34:03 +01:00
kernel bpf: Add schedule points in batch ops 2022-03-02 11:47:56 +01:00
lib lib/iov_iter: initialize "flags" in new pipe_buffer 2022-02-23 12:03:20 +01:00
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mm mm/filemap: Fix handling of THPs in generic_file_buffered_read() 2022-03-02 11:47:47 +01:00
net net-timestamp: convert sk->sk_tskey to atomic_t 2022-03-02 11:48:01 +01:00
samples samples: bpf: Fix 'unknown warning group' build warning on Clang 2022-01-27 11:03:29 +01:00
scripts kconfig: fix failing to generate auto.conf 2022-02-23 12:03:20 +01:00
security selinux: fix misuse of mutex_is_locked() 2022-03-02 11:47:48 +01:00
sound ASoC: qcom: Actually clear DMA interrupt register for HDMI 2022-02-23 12:03:15 +01:00
tools selftests: bpf: Check bpf_msg_push_data return value 2022-03-02 11:47:55 +01:00
usr usr/include/Makefile: add linux/nfc.h to the compile-test coverage 2022-02-01 17:27:15 +01:00
virt KVM: eventfd: Fix false positive RCU usage warning 2022-02-16 12:56:16 +01:00
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CREDITS MAINTAINERS: Move Daniel Drake to credits 2021-09-21 08:34:58 +03:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS drm fixes for 5.15 final 2021-10-28 12:17:01 -07:00
Makefile Linux 5.15.25 2022-02-23 12:03:22 +01:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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.