[PATCH] netfilter: nfnl_cthelper: apply per-class values when updating policies

[David Carlier <devnexen@gmail.com>]

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>
---
 net/netfilter/nfnetlink_cthelper.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/netfilter/nfnetlink_cthelper.c b/net/netfilter/nfnetlink_cthelper.c
index 0d16ad82d70c..34af6840803e 100644
--- a/net/netfilter/nfnetlink_cthelper.c
+++ b/net/netfilter/nfnetlink_cthelper.c
@@ -346,8 +346,8 @@ static int nfnl_cthelper_update_policy_all(struct nlattr *tb[],
 	for (i = 0; i < helper->expect_class_max + 1; i++) {
 		policy = (struct nf_conntrack_expect_policy *)
 				&helper->expect_policy[i];
-		policy->max_expected = new_policy->max_expected;
-		policy->timeout	= new_policy->timeout;
+		policy->max_expected = new_policy[i].max_expected;
+		policy->timeout	= new_policy[i].timeout;
 	}
 
 err:
-- 
2.53.0