Backport fix for crypto: algif_skcipher - Require setkey before accept(2)

Backport fix for 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 4.1 by Milan Broz <gmazyland@gmail.com>]

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