Zhihao Cheng 9aa191b69a ubi: check kthread_should_stop() after the setting of task state ... commit d005f8c6588efcfbe88099b6edafc6f58c84a9c1 upstream. A detach hung is possible when a race occurs between the detach process and the ubi background thread. The following sequences outline the race: ubi thread: if (list_empty(&ubi->works)... ubi detach: set_bit(KTHREAD_SHOULD_STOP, &kthread->flags) => by kthread_stop() wake_up_process() => ubi thread is still running, so 0 is returned ubi thread: set_current_state(TASK_INTERRUPTIBLE) schedule() => ubi thread will never be scheduled again ubi detach: wait_for_completion() => hung task! To fix that, we need to check kthread_should_stop() after we set the task state, so the ubi thread will either see the stop bit and exit or the task state is reset to runnable such that it isn't scheduled out indefinitely. Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com> Cc: <stable@vger.kernel.org> Fixes: 801c135ce7 ("UBI: Unsorted Block Images") Reported-by: syzbot+853639d0cb16c31c7a14@syzkaller.appspotmail.com Signed-off-by: Richard Weinberger <richard@nod.at> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		2020-11-05 11:08:52 +01:00
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attach.c
block.c
build.c
cdev.c
debug.c
debug.h
eba.c
fastmap-wl.c
fastmap.c
gluebi.c
io.c
kapi.c
Kconfig
Makefile
misc.c
ubi-media.h
ubi.h
upd.c
vmt.c
vtbl.c
wl.c	ubi: check kthread_should_stop() after the setting of task state	2020-11-05 11:08:52 +01:00
wl.h