netdev - [PATCH v2] net: bridge: enfore alignment for ethernet address

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Date:   Thu, 25 Jun 2020 14:26:03 +0200
From:   Thomas Martitz <t.martitz@....de>
To:     netdev@...r.kernel.org
Cc:     Thomas Martitz <t.martitz@....de>,
        Roopa Prabhu <roopa@...ulusnetworks.com>,
        Nikolay Aleksandrov <nikolay@...ulusnetworks.com>,
        "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>, Felix Fietkau <nbd@....name>,
        stable@...r.kernel.org
Subject: [PATCH v2] net: bridge: enfore alignment for ethernet address

The eth_addr member is passed to ether_addr functions that require
2-byte alignment, therefore the member must be properly aligned
to avoid unaligned accesses.

The problem is in place since the initial merge of multicast to unicast:
commit 6db6f0eae6052b70885562e1733896647ec1d807 bridge: multicast to unicast

Fixes: 6db6f0eae605 ("bridge: multicast to unicast")
Cc: Roopa Prabhu <roopa@...ulusnetworks.com>
Cc: Nikolay Aleksandrov <nikolay@...ulusnetworks.com>
Cc: David S. Miller <davem@...emloft.net>
Cc: Jakub Kicinski <kuba@...nel.org>
Cc: Felix Fietkau <nbd@....name>
Cc: stable@...r.kernel.org
Signed-off-by: Thomas Martitz <t.martitz@....de>
---
 net/bridge/br_private.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
index 7501be4eeba0..2130fe0194e6 100644
--- a/net/bridge/br_private.h
+++ b/net/bridge/br_private.h
@@ -217,8 +217,8 @@ struct net_bridge_port_group {
 	struct rcu_head			rcu;
 	struct timer_list		timer;
 	struct br_ip			addr;
+	unsigned char			eth_addr[ETH_ALEN] __aligned(2);
 	unsigned char			flags;
-	unsigned char			eth_addr[ETH_ALEN];
 };
 
 struct net_bridge_mdb_entry {
-- 
2.27.0