Linux Ethernet Bridging - Sep 2020 - [Bridge] [PATCH net-next] bridge: mcast: Fix incomplete MDB dump

From: Ido Schimmel <idosch at nvidia.com>

Each MDB entry is encoded in a nested netlink attribute called
'MDBA_MDB_ENTRY'. In turn, this attribute contains another nested
attributed called 'MDBA_MDB_ENTRY_INFO', which encodes a single port
group entry within the MDB entry.

The cited commit added the ability to restart a dump from a specific
port group entry. However, on failure to add a port group entry to the
dump the entire MDB entry (stored in 'nest2') is removed, resulting in
missing port group entries.

Fix this by finalizing the MDB entry with the partial list of already
encoded port group entries.

Fixes: 5205e919c9f0 ("net: bridge: mcast: add support for src list and
filter mode dumping")
Signed-off-by: Ido Schimmel <idosch at nvidia.com>
Acked-by: Nikolay Aleksandrov <nikolay at nvidia.com>
Reviewed-by: Jiri Pirko <jiri at nvidia.com>
---
 net/bridge/br_mdb.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/bridge/br_mdb.c b/net/bridge/br_mdb.c
index 67e0976aeed2..00f1651a6aba 100644
--- a/net/bridge/br_mdb.c
+++ b/net/bridge/br_mdb.c
@@ -243,7 +243,7 @@ static int br_mdb_fill_info(struct sk_buff *skb, struct
netlink_callback *cb,
 
 			err = __mdb_fill_info(skb, mp, p);
 			if (err) {
-				nla_nest_cancel(skb, nest2);
+				nla_nest_end(skb, nest2);
 				goto out;
 			}
 skip_pg:
-- 
2.26.2

From: Ido Schimmel <idosch at idosch.org>
Date: Fri, 11 Sep 2020 16:24:47 +0300
> From: Ido Schimmel <idosch at nvidia.com>
> 
> Each MDB entry is encoded in a nested netlink attribute called
> 'MDBA_MDB_ENTRY'. In turn, this attribute contains another nested
> attributed called 'MDBA_MDB_ENTRY_INFO', which encodes a single
port
> group entry within the MDB entry.
> 
> The cited commit added the ability to restart a dump from a specific
> port group entry. However, on failure to add a port group entry to the
> dump the entire MDB entry (stored in 'nest2') is removed, resulting
in
> missing port group entries.
> 
> Fix this by finalizing the MDB entry with the partial list of already
> encoded port group entries.
> 
> Fixes: 5205e919c9f0 ("net: bridge: mcast: add support for src list and
filter mode dumping")
> Signed-off-by: Ido Schimmel <idosch at nvidia.com>
> Acked-by: Nikolay Aleksandrov <nikolay at nvidia.com>
> Reviewed-by: Jiri Pirko <jiri at nvidia.com>
Applied, thank you.