linux-kernel - [PATCH] net: sched: fix memory leak in tcindex_partial_destroy

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Date:   Sat, 17 Jul 2021 14:29:33 +0300
From:   Pavel Skripkin <paskripkin@...il.com>
To:     jhs@...atatu.com, xiyou.wangcong@...il.com, jiri@...nulli.us,
        davem@...emloft.net
Cc:     netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        Pavel Skripkin <paskripkin@...il.com>,
        syzbot+f0bbb2287b8993d4fa74@...kaller.appspotmail.com
Subject: [PATCH] net: sched: fix memory leak in tcindex_partial_destroy_work

Syzbot reported memory leak in tcindex_set_parms(). The problem was in
non-freed perfect hash in tcindex_partial_destroy_work().

In tcindex_set_parms() new tcindex_data is allocated and some fields from
old one are copied to new one, but not the perfect hash. Since
tcindex_partial_destroy_work() is the destroy function for old
tcindex_data, we need to free perfect hash to avoid memory leak.

Reported-and-tested-by: syzbot+f0bbb2287b8993d4fa74@...kaller.appspotmail.com
Fixes: 331b72922c5f ("net: sched: RCU cls_tcindex")
Signed-off-by: Pavel Skripkin <paskripkin@...il.com>
---
 net/sched/cls_tcindex.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/net/sched/cls_tcindex.c b/net/sched/cls_tcindex.c
index c4007b9cd16d..7ffc7be1e05d 100644
--- a/net/sched/cls_tcindex.c
+++ b/net/sched/cls_tcindex.c
@@ -278,6 +278,8 @@ static int tcindex_filter_result_init(struct tcindex_filter_result *r,
 			     TCA_TCINDEX_POLICE);
 }
 
+static void tcindex_free_perfect_hash(struct tcindex_data *cp);
+
 static void tcindex_partial_destroy_work(struct work_struct *work)
 {
 	struct tcindex_data *p = container_of(to_rcu_work(work),
@@ -285,7 +287,8 @@ static void tcindex_partial_destroy_work(struct work_struct *work)
 					      rwork);
 
 	rtnl_lock();
-	kfree(p->perfect);
+	if (p->perfect)
+		tcindex_free_perfect_hash(p);
 	kfree(p);
 	rtnl_unlock();
 }
-- 
2.32.0