netfilter: nfnl_cthelper: apply per-class values when updating policies

netfilter: nfnl_cthelper: apply per-class values when updating policies

When a userspace conntrack helper with multiple expectation classes is
updated via nfnetlink, every class ends up with the first class's
max_expected and timeout values.

nfnl_cthelper_update_policy_all() validates each new policy into the
corresponding slot of the temporary new_policy array, but the second
loop that commits the values into the live helper dereferences
new_policy as a pointer instead of indexing it, so every iteration
reads new_policy[0] regardless of i.  An update that changes per-class
values is silently collapsed onto class 0's values with no error
returned to userspace.

Index the temporary array by i in the commit loop so each class gets
its own validated values.

Fixes: 2c422257550f ("netfilter: nfnl_cthelper: fix runtime expectation policy updates")
Cc: stable@vger.kernel.org
Signed-off-by: David Carlier <devnexen@gmail.com>
Signed-off-by: Florian Westphal <fw@strlen.de>