Linux Ethernet Bridging - Oct 2020 - [Bridge] [PATCH net-next] net: bridge: explicitly convert between mdb entry state and port group flags

When creating a new multicast port group, there is implicit conversion
between the __u8 state member of struct br_mdb_entry and the unsigned
char flags member of struct net_bridge_port_group. This implicit
conversion relies on the fact that MDB_PERMANENT is equal to
MDB_PG_FLAGS_PERMANENT.

Let's be more explicit and convert the state to flags manually.

Signed-off-by: Vladimir Oltean <vladimir.oltean at nxp.com>
---
 net/bridge/br_mdb.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/net/bridge/br_mdb.c b/net/bridge/br_mdb.c
index 3c8863418d0b..8846c5bcd075 100644
--- a/net/bridge/br_mdb.c
+++ b/net/bridge/br_mdb.c
@@ -846,6 +846,7 @@ static int br_mdb_add_group(struct net_bridge *br, struct
net_bridge_port *port,
 	struct net_bridge_port_group __rcu **pp;
 	struct br_ip group, star_group;
 	unsigned long now = jiffies;
+	unsigned char flags = 0;
 	u8 filter_mode;
 	int err;
 
@@ -904,7 +905,10 @@ static int br_mdb_add_group(struct net_bridge *br, struct
net_bridge_port *port,
 	filter_mode = br_multicast_is_star_g(&group) ? MCAST_EXCLUDE :
 						       MCAST_INCLUDE;
 
-	p = br_multicast_new_port_group(port, &group, *pp, entry->state, NULL,
+	if (entry->state == MDB_PERMANENT)
+		flags |= MDB_PG_FLAGS_PERMANENT;
+
+	p = br_multicast_new_port_group(port, &group, *pp, flags, NULL,
 					filter_mode, RTPROT_STATIC);
 	if (unlikely(!p)) {
 		NL_SET_ERR_MSG_MOD(extack, "Couldn't allocate new port group");
-- 
2.25.1

On Thu, 29 Oct 2020 01:48:15 +0200 Vladimir Oltean
wrote:
> When creating a new multicast port group, there is implicit conversion
> between the __u8 state member of struct br_mdb_entry and the unsigned
> char flags member of struct net_bridge_port_group. This implicit
> conversion relies on the fact that MDB_PERMANENT is equal to
> MDB_PG_FLAGS_PERMANENT.
> 
> Let's be more explicit and convert the state to flags manually.
> 
> Signed-off-by: Vladimir Oltean <vladimir.oltean at nxp.com>
Applied, thanks!