linux-kernel - [PATCH 4.20 57/76] net/sched: act_ipt: fix refcount leak when replace fails

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Date:   Fri,  8 Mar 2019 13:50:09 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Davide Caratti <dcaratti@...hat.com>,
        "David S. Miller" <davem@...emloft.net>
Subject: [PATCH 4.20 57/76] net/sched: act_ipt: fix refcount leak when replace fails

4.20-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Davide Caratti <dcaratti@...hat.com>

[ Upstream commit 8f67c90ee9148eab3d2b4393c3cf76489b27f87c ]

After commit 4e8ddd7f1758 ("net: sched: don't release reference on action
overwrite"), the error path of all actions was converted to drop refcount
also when the action was being overwritten. But we forgot act_ipt_init(),
in case allocation of 'tname' was not successful:

 # tc action add action xt -j LOG --log-prefix hello index 100
 tablename: mangle hook: NF_IP_POST_ROUTING
         target:  LOG level warning prefix "hello" index 100
 # tc action show action xt
 total acts 1

         action order 0: tablename: mangle  hook: NF_IP_POST_ROUTING
         target  LOG level warning prefix "hello"
         index 100 ref 1 bind 0
 # tc action replace action xt -j LOG --log-prefix world index 100
 tablename: mangle hook: NF_IP_POST_ROUTING
         target:  LOG level warning prefix "world" index 100
 RTNETLINK answers: Cannot allocate memory
 We have an error talking to the kernel
 # tc action show action xt
 total acts 1

         action order 0: tablename: mangle  hook: NF_IP_POST_ROUTING
         target  LOG level warning prefix "hello"
         index 100 ref 2 bind 0

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

Fixes: 4e8ddd7f1758 ("net: sched: don't release reference on action overwrite")
Signed-off-by: Davide Caratti <dcaratti@...hat.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 net/sched/act_ipt.c |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

--- a/net/sched/act_ipt.c
+++ b/net/sched/act_ipt.c
@@ -199,8 +199,7 @@ err3:
 err2:
 	kfree(tname);
 err1:
-	if (ret == ACT_P_CREATED)
-		tcf_idr_release(*a, bind);
+	tcf_idr_release(*a, bind);
 	return err;
 }