netdev - [PATCH net v2] net: bridge: fix memleak in br_add

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Date:   Mon, 9 Aug 2021 17:02:11 +0800
From:   Yang Yingliang <yangyingliang@...wei.com>
To:     <linux-kernel@...r.kernel.org>, <netdev@...r.kernel.org>,
        <bridge@...ts.linux-foundation.org>
CC:     <roopa@...dia.com>, <nikolay@...dia.com>, <davem@...emloft.net>,
        <kuba@...nel.org>
Subject: [PATCH net v2] net: bridge: fix memleak in br_add_if()

I got a memleak report:

BUG: memory leak
unreferenced object 0x607ee521a658 (size 240):
comm "syz-executor.0", pid 955, jiffies 4294780569 (age 16.449s)
hex dump (first 32 bytes, cpu 1):
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
backtrace:
[<00000000d830ea5a>] br_multicast_add_port+0x1c2/0x300 net/bridge/br_multicast.c:1693
[<00000000274d9a71>] new_nbp net/bridge/br_if.c:435 [inline]
[<00000000274d9a71>] br_add_if+0x670/0x1740 net/bridge/br_if.c:611
[<0000000012ce888e>] do_set_master net/core/rtnetlink.c:2513 [inline]
[<0000000012ce888e>] do_set_master+0x1aa/0x210 net/core/rtnetlink.c:2487
[<0000000099d1cafc>] __rtnl_newlink+0x1095/0x13e0 net/core/rtnetlink.c:3457
[<00000000a01facc0>] rtnl_newlink+0x64/0xa0 net/core/rtnetlink.c:3488
[<00000000acc9186c>] rtnetlink_rcv_msg+0x369/0xa10 net/core/rtnetlink.c:5550
[<00000000d4aabb9c>] netlink_rcv_skb+0x134/0x3d0 net/netlink/af_netlink.c:2504
[<00000000bc2e12a3>] netlink_unicast_kernel net/netlink/af_netlink.c:1314 [inline]
[<00000000bc2e12a3>] netlink_unicast+0x4a0/0x6a0 net/netlink/af_netlink.c:1340
[<00000000e4dc2d0e>] netlink_sendmsg+0x789/0xc70 net/netlink/af_netlink.c:1929
[<000000000d22c8b3>] sock_sendmsg_nosec net/socket.c:654 [inline]
[<000000000d22c8b3>] sock_sendmsg+0x139/0x170 net/socket.c:674
[<00000000e281417a>] ____sys_sendmsg+0x658/0x7d0 net/socket.c:2350
[<00000000237aa2ab>] ___sys_sendmsg+0xf8/0x170 net/socket.c:2404
[<000000004f2dc381>] __sys_sendmsg+0xd3/0x190 net/socket.c:2433
[<0000000005feca6c>] do_syscall_64+0x37/0x90 arch/x86/entry/common.c:47
[<000000007304477d>] entry_SYSCALL_64_after_hwframe+0x44/0xae

On error path of br_add_if(), p->mcast_stats allocated in
new_nbp() need be freed, or it will be leaked.

Fixes: 1080ab95e3c7 ("net: bridge: add support for IGMP/MLD stats and export them via netlink")
Reported-by: Hulk Robot <hulkci@...wei.com>
Signed-off-by: Yang Yingliang <yangyingliang@...wei.com>
---
v2:
  move free_percpu(p->mcast_stats) in release_nbp() and
  fix the compile error when CONFIG_BRIDGE_IGMP_SNOOPING
  is disabled.
---
 net/bridge/br_if.c        | 5 ++++-
 net/bridge/br_multicast.c | 1 -
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/net/bridge/br_if.c b/net/bridge/br_if.c
index 6e4a32354a13..c5547772614a 100644
--- a/net/bridge/br_if.c
+++ b/net/bridge/br_if.c
@@ -250,6 +250,9 @@ static void release_nbp(struct kobject *kobj)
 {
 	struct net_bridge_port *p
 		= container_of(kobj, struct net_bridge_port, kobj);
+#if IS_ENABLED(CONFIG_BRIDGE_IGMP_SNOOPING)
+	free_percpu(p->mcast_stats);
+#endif
 	kfree(p);
 }
 
@@ -616,7 +619,7 @@ int br_add_if(struct net_bridge *br, struct net_device *dev,
 
 	err = dev_set_allmulti(dev, 1);
 	if (err) {
-		kfree(p);	/* kobject not yet init'd, manually free */
+		release_nbp(&p->kobj);	/* kobject not yet init'd, manually free */
 		goto err1;
 	}
 
diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c
index d0434dc8c03b..1d3436279d2f 100644
--- a/net/bridge/br_multicast.c
+++ b/net/bridge/br_multicast.c
@@ -1715,7 +1715,6 @@ void br_multicast_del_port(struct net_bridge_port *port)
 #if IS_ENABLED(CONFIG_IPV6)
 	del_timer_sync(&port->ip6_mc_router_timer);
 #endif
-	free_percpu(port->mcast_stats);
 }
 
 static void br_multicast_enable(struct bridge_mcast_own_query *query)
-- 
2.25.1