From 36a50a989ee8267588de520b8704b85f045a3220 Mon Sep 17 00:00:00 2001 From: Tung Nguyen Date: Tue, 17 Apr 2018 21:58:27 +0200 Subject: [PATCH] tipc: fix infinite loop when dumping link monitor summary When configuring the number of used bearers to MAX_BEARER and issuing command "tipc link monitor summary", the command enters infinite loop in user space. This issue happens because function tipc_nl_node_dump_monitor() returns the wrong 'prev_bearer' value when all potential monitors have been scanned. The correct behavior is to always try to scan all monitors until either the netlink message is full, in which case we return the bearer identity of the affected monitor, or we continue through the whole bearer array until we can return MAX_BEARERS. This solution also caters for the case where there may be gaps in the bearer array. Signed-off-by: Tung Nguyen Signed-off-by: Jon Maloy Signed-off-by: David S. Miller --- net/tipc/monitor.c | 2 +- net/tipc/node.c | 11 ++++------- 2 files changed, 5 insertions(+), 8 deletions(-) diff --git a/net/tipc/monitor.c b/net/tipc/monitor.c index 32dc33a94bc7..5453e564da82 100644 --- a/net/tipc/monitor.c +++ b/net/tipc/monitor.c @@ -777,7 +777,7 @@ int __tipc_nl_add_monitor(struct net *net, struct tipc_nl_msg *msg, ret = tipc_bearer_get_name(net, bearer_name, bearer_id); if (ret || !mon) - return -EINVAL; + return 0; hdr = genlmsg_put(msg->skb, msg->portid, msg->seq, &tipc_genl_family, NLM_F_MULTI, TIPC_NL_MON_GET); diff --git a/net/tipc/node.c b/net/tipc/node.c index c77dd2f3c589..6f98b56dd48e 100644 --- a/net/tipc/node.c +++ b/net/tipc/node.c @@ -2232,8 +2232,8 @@ int tipc_nl_node_dump_monitor(struct sk_buff *skb, struct netlink_callback *cb) struct net *net = sock_net(skb->sk); u32 prev_bearer = cb->args[0]; struct tipc_nl_msg msg; + int bearer_id; int err; - int i; if (prev_bearer == MAX_BEARERS) return 0; @@ -2243,16 +2243,13 @@ int tipc_nl_node_dump_monitor(struct sk_buff *skb, struct netlink_callback *cb) msg.seq = cb->nlh->nlmsg_seq; rtnl_lock(); - for (i = prev_bearer; i < MAX_BEARERS; i++) { - prev_bearer = i; + for (bearer_id = prev_bearer; bearer_id < MAX_BEARERS; bearer_id++) { err = __tipc_nl_add_monitor(net, &msg, prev_bearer); if (err) - goto out; + break; } - -out: rtnl_unlock(); - cb->args[0] = prev_bearer; + cb->args[0] = bearer_id; return skb->len; }