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    Subject[PATCH 4.19 049/103] tty/n_hdlc: fix __might_sleep warning
    Date
    4.19-stable review patch.  If anyone has any objections, please let me know.

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

    From: Paul Fulghum <paulkf@microgate.com>

    commit fc01d8c61ce02c034e67378cd3e645734bc18c8c upstream.

    Fix __might_sleep warning[1] in tty/n_hdlc.c read due to copy_to_user
    call while current is TASK_INTERRUPTIBLE. This is a false positive
    since the code path does not depend on current state remaining
    TASK_INTERRUPTIBLE. The loop breaks out and sets TASK_RUNNING after
    calling copy_to_user.

    This patch supresses the warning by setting TASK_RUNNING before calling
    copy_to_user.

    [1] https://syzkaller.appspot.com/bug?id=17d5de7f1fcab794cb8c40032f893f52de899324

    Signed-off-by: Paul Fulghum <paulkf@microgate.com>
    Reported-by: syzbot <syzbot+c244af085a0159d22879@syzkaller.appspotmail.com>
    Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
    Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
    Cc: stable <stable@vger.kernel.org>
    Acked-by: Arnd Bergmann <arnd@arndb.de>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    drivers/tty/n_hdlc.c | 1 +
    1 file changed, 1 insertion(+)

    --- a/drivers/tty/n_hdlc.c
    +++ b/drivers/tty/n_hdlc.c
    @@ -597,6 +597,7 @@ static ssize_t n_hdlc_tty_read(struct tt
    /* too large for caller's buffer */
    ret = -EOVERFLOW;
    } else {
    + __set_current_state(TASK_RUNNING);
    if (copy_to_user(buf, rbuf->buf, rbuf->count))
    ret = -EFAULT;
    else

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