crypto: echainiv - Replace chaining with multiplication

crypto: echainiv - Replace chaining with multiplication

commit 53a5d5ddccf849dbc27a8c1bba0b43c3a45fb792 upstream.

The current implementation uses a global per-cpu array to store
data which are used to derive the next IV.  This is insecure as
the attacker may change the stored data.

This patch removes all traces of chaining and replaces it with
multiplication of the salt and the sequence number.

Fixes: a10f554fa7e0 ("crypto: echainiv - Add encrypted chain IV...")
Reported-by: Mathias Krause <minipli@googlemail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>