netdev - [PATCH net] net/sched: act_skbedit: fix refcount leak when replace fails

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Message-Id: <8f12357dd5131d64326b05ac5b71eb847afb692a.1550834944.git.dcaratti@redhat.com>
Date:   Fri, 22 Feb 2019 12:33:26 +0100
From:   Davide Caratti <dcaratti@...hat.com>
To:     Vlad Buslov <vladbu@...lanox.com>,
        Cong Wang <xiyou.wangcong@...il.com>,
        Jamal Hadi Salim <jhs@...atatu.com>,
        Jiri Pirko <jiri@...nulli.us>,
        "David S. Miller" <davem@...emloft.net>
Cc:     netdev@...r.kernel.org
Subject: [PATCH net] net/sched: act_skbedit: fix refcount leak when replace fails

when act_skbedit was converted to use RCU in the data plane, we added an
error path, but we forgot to drop the action refcount in case of failure
during a 'replace' operation:

 # tc actions add action skbedit ptype otherhost pass index 100
 # tc action show action skbedit
 total acts 1

         action order 0: skbedit  ptype otherhost pass
          index 100 ref 1 bind 0
 # tc actions replace action skbedit ptype otherhost drop index 100
 RTNETLINK answers: Cannot allocate memory
 We have an error talking to the kernel
 # tc action show action skbedit
 total acts 1

         action order 0: skbedit  ptype otherhost pass
          index 100 ref 2 bind 0

Ensure we call tcf_idr_release(), in case 'params_new' allocation failed,
also when the action is being replaced.

Fixes: c749cdda9089 ("net/sched: act_skbedit: don't use spinlock in the data path")
Signed-off-by: Davide Caratti <dcaratti@...hat.com>
---
 net/sched/act_skbedit.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/net/sched/act_skbedit.c b/net/sched/act_skbedit.c
index 64dba3708fce..cfceed28c333 100644
--- a/net/sched/act_skbedit.c
+++ b/net/sched/act_skbedit.c
@@ -189,8 +189,7 @@ static int tcf_skbedit_init(struct net *net, struct nlattr *nla,
 
 	params_new = kzalloc(sizeof(*params_new), GFP_KERNEL);
 	if (unlikely(!params_new)) {
-		if (ret == ACT_P_CREATED)
-			tcf_idr_release(*a, bind);
+		tcf_idr_release(*a, bind);
 		return -ENOMEM;
 	}
 
-- 
2.20.1