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    Subject[PATCH 4.14 056/165] ipc/sem.c: prevent queue.status tearing in semop
    Date
    4.14-stable review patch.  If anyone has any objections, please let me know.

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

    From: Davidlohr Bueso <dave@stgolabs.net>

    [ Upstream commit f075faa300acc4f6301e348acde0a4580ed5f77c ]

    In order for load/store tearing prevention to work, _all_ accesses to
    the variable in question need to be done around READ and WRITE_ONCE()
    macros. Ensure everyone does so for q->status variable for
    semtimedop().

    Link: http://lkml.kernel.org/r/20180717052654.676-1-dave@stgolabs.net
    Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
    Cc: Manfred Spraul <manfred@colorfullife.com>
    Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
    Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
    Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    ipc/sem.c | 2 +-
    1 file changed, 1 insertion(+), 1 deletion(-)

    --- a/ipc/sem.c
    +++ b/ipc/sem.c
    @@ -2041,7 +2041,7 @@ static long do_semtimedop(int semid, str
    }

    do {
    - queue.status = -EINTR;
    + WRITE_ONCE(queue.status, -EINTR);
    queue.sleeper = current;

    __set_current_state(TASK_INTERRUPTIBLE);

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