linux-kernel - [PATCH 4.9 02/78] act_ife: fix a potential use-after-free

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Message-Id: <20180913131805.866644287@linuxfoundation.org>
Date:   Thu, 13 Sep 2018 15:30:49 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Jamal Hadi Salim <jhs@...atatu.com>,
        Cong Wang <xiyou.wangcong@...il.com>,
        "David S. Miller" <davem@...emloft.net>
Subject: [PATCH 4.9 02/78] act_ife: fix a potential use-after-free

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

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

From: Cong Wang <xiyou.wangcong@...il.com>

[ Upstream commit 6d784f1625ea68783cc1fb17de8f6cd3e1660c3f ]

Immediately after module_put(), user could delete this
module, so e->ops could be already freed before we call
e->ops->release().

Fix this by moving module_put() after ops->release().

Fixes: ef6980b6becb ("introduce IFE action")
Cc: Jamal Hadi Salim <jhs@...atatu.com>
Signed-off-by: Cong Wang <xiyou.wangcong@...il.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 net/sched/act_ife.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/net/sched/act_ife.c
+++ b/net/sched/act_ife.c
@@ -395,7 +395,6 @@ static void _tcf_ife_cleanup(struct tc_a
 	struct tcf_meta_info *e, *n;
 
 	list_for_each_entry_safe(e, n, &ife->metalist, metalist) {
-		module_put(e->ops->owner);
 		list_del(&e->metalist);
 		if (e->metaval) {
 			if (e->ops->release)
@@ -403,6 +402,7 @@ static void _tcf_ife_cleanup(struct tc_a
 			else
 				kfree(e->metaval);
 		}
+		module_put(e->ops->owner);
 		kfree(e);
 	}
 }