crypto: algif_skcipher - Require setkey before accept(2)

    commit dd504589577d8e8e70f51f997ad487a4cb6c026f upstream.

    Some cipher implementations will crash if you try to use them
    without calling setkey first.  This patch adds a check so that
    the accept(2) call will fail with -ENOKEY if setkey hasn't been
    done on the socket yet.

    Cc: stable@vger.kernel.org
    Reported-by: Dmitry Vyukov <dvyukov@google.com>
    Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
    Tested-by: Dmitry Vyukov <dvyukov@google.com>
    [backported to 3.18 by Milan Broz <gmazyland@gmail.com>]

Signed-off-by: Sasha Levin <sasha.levin@oracle.com>