[PATCH net] tipc: purge deferredq list for each grp member in tipc_group_delete

[Xin Long]

Syzbot reported a memleak caused by grp members' deferredq list not
purged when the grp is be deleted.

The issue occurs when more(msg_grp_bc_seqno(hdr), m->bc_rcv_nxt) in
tipc_group_filter_msg() and the skb will stay in deferredq.

So fix it by calling __skb_queue_purge for each member's deferredq
in tipc_group_delete() when a tipc sk leaves the grp.

Fixes: b87a5ea31c93 ("tipc: guarantee group unicast doesn't bypass group 
broadcast")
Reported-by: syzbot+78fbe679c8ca8d264...@syzkaller.appspotmail.com
Signed-off-by: Xin Long <lucien....@gmail.com>
---
 net/tipc/group.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/tipc/group.c b/net/tipc/group.c
index 992be61..5f98d38 100644
--- a/net/tipc/group.c
+++ b/net/tipc/group.c
@@ -218,6 +218,7 @@ void tipc_group_delete(struct net *net, struct tipc_group 
*grp)
 
        rbtree_postorder_for_each_entry_safe(m, tmp, tree, tree_node) {
                tipc_group_proto_xmit(grp, m, GRP_LEAVE_MSG, &xmitq);
+               __skb_queue_purge(&m->deferredq);
                list_del(&m->list);
                kfree(m);
        }
-- 
2.1.0