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From:   Jia-Ju Bai <baijiaju1990@gmail.com>
To:     jon.maloy@ericsson.com, ying.xue@windriver.com, davem@davemloft.net
Cc:     netdev@vger.kernel.org, tipc-discussion@lists.sourceforge.net,
        linux-kernel@vger.kernel.org, Jia-Ju Bai <baijiaju1990@gmail.com>
Subject: [PATCH] net: tipc: Fix a possible null-pointer dereference in tipc_publ_purge()
Date:   Thu, 25 Jul 2019 17:20:21 +0800
Message-Id: <20190725092021.15855-1-baijiaju1990@gmail.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

In tipc_publ_purge(), there is an if statement on 215 to 
check whether p is NULL: 
    if (p)

When p is NULL, it is used on line 226:
    kfree_rcu(p, rcu);

Thus, a possible null-pointer dereference may occur.

To fix this bug, p is checked before being used.

This bug is found by a static analysis tool STCheck written by us.

Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
---
 net/tipc/name_distr.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/tipc/name_distr.c b/net/tipc/name_distr.c
index 44abc8e9c990..241ed2274473 100644
--- a/net/tipc/name_distr.c
+++ b/net/tipc/name_distr.c
@@ -223,7 +223,8 @@ static void tipc_publ_purge(struct net *net, struct publication *publ, u32 addr)
 		       publ->key);
 	}
 
-	kfree_rcu(p, rcu);
+	if (p)
+		kfree_rcu(p, rcu);
 }
 
 /**
-- 
2.17.0