CVE-2019-16995: Missing Release of Memory after Effective Lifetime (CWE-401)
value: In the Linux kernel before 5.0.3, a memory leak exits in hsr_dev_finalize() in net/hsr/hsr_device.c if hsr_add_port fails to add a port, which may cause denial of service, aka CID-6caabe7f197d.
CWE description: The product does not sufficiently track and release allocated memory after it has been used, which slowly consumes remaining memory.
CVSS v3 base score: 7.5
Published: 2019-09-30T13:15Z
Repository: https://github.com/torvalds/linux
Language: C
Files changed: net/hsr/hsr_device.c, net/hsr/hsr_framereg.c, net/hsr/hsr_framereg.h
Commit date: 2019-03-06 10:57:05 -0800
Commit message: net: hsr: fix memory leak in hsr_dev_finalize()

If hsr_add_port(hsr, hsr_dev, HSR_PT_MASTER) failed to
add port, it directly returns res and forgets to free the node
that allocated in hsr_create_self_node(), and forgets to delete
the node->mac_list linked in hsr->self_node_db.

BUG: memory leak
unreferenced object 0xffff8881cfa0c780 (size 64):
  comm "syz-executor.0", pid 2077, jiffies 4294717969 (age 2415.377s)
  hex dump (first 32 bytes):
    e0 c7 a0 cf 81 88 ff ff 00 02 00 00 00 00 ad de  ................
    00 e6 49 cd 81 88 ff ff c0 9b 87 d0 81 88 ff ff  ..I.............
  backtrace:
    [<00000000e2ff5070>] hsr_dev_finalize+0x736/0x960 [hsr]
    [<000000003ed2e597>] hsr_newlink+0x2b2/0x3e0 [hsr]
    [<000000003fa8c6b6>] __rtnl_newlink+0xf1f/0x1600 net/core/rtnetlink.c:3182
    [<000000001247a7ad>] rtnl_newlink+0x66/0x90 net/core/rtnetlink.c:3240
    [<00000000e7d1b61d>] rtnetlink_rcv_msg+0x54e/0xb90 net/core/rtnetlink.c:5130
    [<000000005556bd3a>] netlink_rcv_skb+0x129/0x340 net/netlink/af_netlink.c:2477
    [<00000000741d5ee6>] netlink_unicast_kernel net/netlink/af_netlink.c:1310 [inline]
    [<00000000741d5ee6>] netlink_unicast+0x49a/0x650 net/netlink/af_netlink.c:1336
    [<000000009d56f9b7>] netlink_sendmsg+0x88b/0xdf0 net/netlink/af_netlink.c:1917
    [<0000000046b35c59>] sock_sendmsg_nosec net/socket.c:621 [inline]
    [<0000000046b35c59>] sock_sendmsg+0xc3/0x100 net/socket.c:631
    [<00000000d208adc9>] __sys_sendto+0x33e/0x560 net/socket.c:1786
    [<00000000b582837a>] __do_sys_sendto net/socket.c:1798 [inline]
    [<00000000b582837a>] __se_sys_sendto net/socket.c:1794 [inline]
    [<00000000b582837a>] __x64_sys_sendto+0xdd/0x1b0 net/socket.c:1794
    [<00000000c866801d>] do_syscall_64+0x147/0x600 arch/x86/entry/common.c:290
    [<00000000fea382d9>] entry_SYSCALL_64_after_hwframe+0x49/0xbe
    [<00000000e01dacb3>] 0xffffffffffffffff

Fixes: c5a759117210 ("net/hsr: Use list_head (and rcu) instead of array for slave devices.")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Mao Wenan <maowenan@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Diff: diff --git a/net/hsr/hsr_device.c b/net/hsr/hsr_device.c
index b8cd43c9ed5b..c4676bacb8db 100644
--- a/net/hsr/hsr_device.c
+++ b/net/hsr/hsr_device.c
@@ -484,11 +484,11 @@ int hsr_dev_finalize(struct net_device *hsr_dev, struct net_device *slave[2],
 	/* Make sure the 1st call to netif_carrier_on() gets through */
 	netif_carrier_off(hsr_dev);
 
 	res = hsr_add_port(hsr, hsr_dev, HSR_PT_MASTER);
 	if (res)
-		return res;
+		goto err_add_port;
 
 	res = register_netdevice(hsr_dev);
 	if (res)
 		goto fail;
 
@@ -504,8 +504,10 @@ int hsr_dev_finalize(struct net_device *hsr_dev, struct net_device *slave[2],
 	return 0;
 
 fail:
 	hsr_for_each_port(hsr, port)
 		hsr_del_port(port);
+err_add_port:
+	hsr_del_node(&hsr->self_node_db);
 
 	return res;
 }
diff --git a/net/hsr/hsr_framereg.c b/net/hsr/hsr_framereg.c
index 286ceb41ac0c..9af16cb68f76 100644
--- a/net/hsr/hsr_framereg.c
+++ b/net/hsr/hsr_framereg.c
@@ -122,10 +122,22 @@ int hsr_create_self_node(struct list_head *self_node_db,
 	}
 
 	return 0;
 }
 
+void hsr_del_node(struct list_head *self_node_db)
+{
+	struct hsr_node *node;
+
+	rcu_read_lock();
+	node = list_first_or_null_rcu(self_node_db, struct hsr_node, mac_list);
+	rcu_read_unlock();
+	if (node) {
+		list_del_rcu(&node->mac_list);
+		kfree(node);
+	}
+}
 
 /* Allocate an hsr_node and add it to node_db. 'addr' is the node's AddressA;
  * seq_out is used to initialize filtering of outgoing duplicate frames
  * originating from the newly added node.
  */
diff --git a/net/hsr/hsr_framereg.h b/net/hsr/hsr_framereg.h
index 370b45998121..531fd3dfcac1 100644
--- a/net/hsr/hsr_framereg.h
+++ b/net/hsr/hsr_framereg.h
@@ -14,10 +14,11 @@
 
 #include "hsr_main.h"
 
 struct hsr_node;
 
+void hsr_del_node(struct list_head *self_node_db);
 struct hsr_node *hsr_add_node(struct list_head *node_db, unsigned char addr[],
 			      u16 seq_out);
 struct hsr_node *hsr_get_node(struct hsr_port *port, struct sk_buff *skb,
 			      bool is_sup);
 void hsr_handle_sup_frame(struct sk_buff *skb, struct hsr_node *node_curr,

Vulnerable code: 		return res;
Fixed code: 		goto err_add_port;
err_add_port:
	hsr_del_node(&hsr->self_node_db);
void hsr_del_node(struct list_head *self_node_db)
{
	struct hsr_node *node;

	rcu_read_lock();
	node = list_first_or_null_rcu(self_node_db, struct hsr_node, mac_list);
	rcu_read_unlock();
	if (node) {
		list_del_rcu(&node->mac_list);
		kfree(node);
	}
}
void hsr_del_node(struct list_head *self_node_db);