net: ndo_fdb_dump should report -EMSGSIZE to rtnl_fdb_dump.

When the send skbuff reaches the end, nlmsg_put and friends returns
-EMSGSIZE but it is silently thrown away in ndo_fdb_dump. It is called
within a for_each_netdev loop and the first fdb entry of a following
netdev could fit in the remaining skbuff.  This breaks the mechanism
of cb->args[0] and idx to keep track of the entries that are already
dumped, which results missing entries in bridge fdb show command.

Signed-off-by: Minoura Makoto <minoura@valinux.co.jp>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 10 insertions, 5 deletions

diff --git a/net/bridge/br_fdb.c b/net/bridge/br_fdb.c
index 82e3e97..dcea4f4 100644
--- a/net/bridge/br_fdb.c
+++ b/net/bridge/br_fdb.c
@@ -723,6 +723,8 @@ int br_fdb_dump(struct sk_buff *skb,
 		struct net_bridge_fdb_entry *f;
 
 		hlist_for_each_entry_rcu(f, &br->hash[i], hlist) {
+			int err;
+
 			if (idx < cb->args[0])
 				goto skip;
 
@@ -741,12 +743,15 @@ int br_fdb_dump(struct sk_buff *skb,
 			if (!filter_dev && f->dst)
 				goto skip;
 
-			if (fdb_fill_info(skb, br, f,
-					  NETLINK_CB(cb->skb).portid,
-					  cb->nlh->nlmsg_seq,
-					  RTM_NEWNEIGH,
-					  NLM_F_MULTI) < 0)
+			err = fdb_fill_info(skb, br, f,
+					    NETLINK_CB(cb->skb).portid,
+					    cb->nlh->nlmsg_seq,
+					    RTM_NEWNEIGH,
+					    NLM_F_MULTI);
+			if (err < 0) {
+				cb->args[1] = err;
 				break;
+			}
 skip:
 			++idx;
 		}