[PATCH 4.20 58/76] net/sched: act_skbedit: fix refcount leak when replace fails

Greg Kroah-Hartman
2019-03-08T12:56:14Z

From: Davide Caratti <dcaratti@redhat.com>

[ Upstream commit 6191da98062d25276a3b88fb2a94dcbcfb3ea65d ]

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@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/sched/act_skbedit.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)

--- a/net/sched/act_skbedit.c
+++ b/net/sched/act_skbedit.c
@@ -189,8 +189,7 @@ static int tcf_skbedit_init(struct net *

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;
}