nilfs2: fix use-after-free of timer for log writer thread

stable inclusion
from stable-v4.19.316
commit 822ae5a8eac30478578a75f7e064f0584931bf2d
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/IA6S5D
CVE: CVE-2024-38583

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=822ae5a8eac30478578a75f7e064f0584931bf2d

--------------------------------

commit f5d4e04634c9cf68bdf23de08ada0bb92e8befe7 upstream.

Patch series "nilfs2: fix log writer related issues".

This bug fix series covers three nilfs2 log writer-related issues,
including a timer use-after-free issue and potential deadlock issue on
unmount, and a potential freeze issue in event synchronization found
during their analysis.  Details are described in each commit log.

This patch (of 3):

A use-after-free issue has been reported regarding the timer sc_timer on
the nilfs_sc_info structure.

The problem is that even though it is used to wake up a sleeping log
writer thread, sc_timer is not shut down until the nilfs_sc_info structure
is about to be freed, and is used regardless of the thread's lifetime.

Fix this issue by limiting the use of sc_timer only while the log writer
thread is alive.

Link: https://lkml.kernel.org/r/20240520132621.4054-1-konishi.ryusuke@gmail.com
Link: https://lkml.kernel.org/r/20240520132621.4054-2-konishi.ryusuke@gmail.com


Fixes: fdce895e ("nilfs2: change sc_timer from a pointer to an embedded one in struct nilfs_sc_info")
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Reported-by: "Bai, Shuangpeng" <sjb7183@psu.edu>
Closes: https://groups.google.com/g/syzkaller/c/MK_LYqtt8ko/m/8rgdWeseAwAJ


Tested-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Conflicts:
	fs/nilfs2/segment.c
[context conflict]
Signed-off-by: Guo Mengqi <guomengqi3@huawei.com>