bonding: fix null pointer deref in bond_ipsec_offload_ok

BugLink: https://bugs.launchpad.net/bugs/2080594

[ Upstream commit 95c90e4ad89d493a7a14fa200082e466e2548f9d ]

We must check if there is an active slave before dereferencing the pointer.

Fixes: 18cb261 ("bonding: support hardware encryption offload to slaves")
Signed-off-by: Nikolay Aleksandrov <[email protected]>
Reviewed-by: Hangbin Liu <[email protected]>
Reviewed-by: Eric Dumazet <[email protected]>
Signed-off-by: Paolo Abeni <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>
Signed-off-by: Koichiro Den <[email protected]>
Signed-off-by: Stefan Bader <[email protected]>

Author: NikAleksandrov

drivers/net/bonding/bond_main.c

@@ -597,6 +597,8 @@ static bool bond_ipsec_offload_ok(struct sk_buff *skb, struct xfrm_state *xs)
 	bond = netdev_priv(bond_dev);
 	rcu_read_lock();
 	curr_active = rcu_dereference(bond->curr_active_slave);
+	if (!curr_active)
+		goto out;
 	real_dev = curr_active->dev;
 
 	if (BOND_MODE(bond) != BOND_MODE_ACTIVEBACKUP)