Zhihao Cheng da3bb6fa23 ubi: check kthread_should_stop() after the setting of task state ... commit d005f8c658 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 11:43:33 +01:00
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attach.c
block.c
build.c
cdev.c
debug.c
debug.h
eba.c
fastmap-wl.c	ubi: fastmap: Free unused fastmap anchor peb during detach	2020-10-01 13:18:11 +02:00
fastmap.c	ubi: Fix producing anchor PEBs	2020-10-01 13:17:19 +02:00
gluebi.c
io.c
kapi.c
Kconfig
Makefile
misc.c
ubi-media.h
ubi.h	ubi: Fix producing anchor PEBs	2020-10-01 13:17:19 +02:00
upd.c
vmt.c
vtbl.c
wl.c	ubi: check kthread_should_stop() after the setting of task state	2020-11-05 11:43:33 +01:00
wl.h	ubi: Fix producing anchor PEBs	2020-10-01 13:17:19 +02:00