[PATCH -next v2] netlabel: Fix memory leak in netlbl_mgmt_add_common

[Liu Shixin]

Hulk Robot reported memory leak in netlbl_mgmt_add_common.
The problem is non-freed map in case of netlbl_domhsh_add() failed.

BUG: memory leak
unreferenced object 0xffff888100ab7080 (size 96):
  comm "syz-executor537", pid 360, jiffies 4294862456 (age 22.678s)
  hex dump (first 32 bytes):
    05 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
    fe 00 00 00 00 00 00 00 00 00 00 00 00 00 00 01  ................
  backtrace:
    [<0000000008b40026>] netlbl_mgmt_add_common.isra.0+0xb2a/0x1b40
    [<000000003be10950>] netlbl_mgmt_add+0x271/0x3c0
    [<00000000c70487ed>] genl_family_rcv_msg_doit.isra.0+0x20e/0x320
    [<000000001f2ff614>] genl_rcv_msg+0x2bf/0x4f0
    [<0000000089045792>] netlink_rcv_skb+0x134/0x3d0
    [<0000000020e96fdd>] genl_rcv+0x24/0x40
    [<0000000042810c66>] netlink_unicast+0x4a0/0x6a0
    [<000000002e1659f0>] netlink_sendmsg+0x789/0xc70
    [<000000006e43415f>] sock_sendmsg+0x139/0x170
    [<00000000680a73d7>] ____sys_sendmsg+0x658/0x7d0
    [<0000000065cbb8af>] ___sys_sendmsg+0xf8/0x170
    [<0000000019932b6c>] __sys_sendmsg+0xd3/0x190
    [<00000000643ac172>] do_syscall_64+0x37/0x90
    [<000000009b79d6dc>] entry_SYSCALL_64_after_hwframe+0x44/0xae

Fixes: 63c416887437 ("netlabel: Add network address selectors to the NetLabel/LSM domain mapping")
Reported-by: Hulk Robot <hulkci at huawei.com>
Signed-off-by: Liu Shixin <liushixin2 at huawei.com>
---
v1->v2: According to Dongliang's and Paul's advices, simplify the code.

 net/netlabel/netlabel_mgmt.c | 22 +++++++++++++---------
 1 file changed, 13 insertions(+), 9 deletions(-)

diff --git a/net/netlabel/netlabel_mgmt.c b/net/netlabel/netlabel_mgmt.c
index e664ab990941..fa9e68e5f826 100644
--- a/net/netlabel/netlabel_mgmt.c
+++ b/net/netlabel/netlabel_mgmt.c
@@ -76,6 +76,7 @@ static const struct nla_policy netlbl_mgmt_genl_policy[NLBL_MGMT_A_MAX + 1] = {
 static int netlbl_mgmt_add_common(struct genl_info *info,
 				  struct netlbl_audit *audit_info)
 {
+	void * pmap = NULL;
 	int ret_val = -EINVAL;
 	struct netlbl_domaddr_map *addrmap = NULL;
 	struct cipso_v4_doi *cipsov4 = NULL;
@@ -175,6 +176,8 @@ static int netlbl_mgmt_add_common(struct genl_info *info,
 			ret_val = -ENOMEM;
 			goto add_free_addrmap;
 		}
+
+		pmap = map;
 		map->list.addr = addr->s_addr & mask->s_addr;
 		map->list.mask = mask->s_addr;
 		map->list.valid = 1;
@@ -183,14 +186,13 @@ static int netlbl_mgmt_add_common(struct genl_info *info,
 			map->def.cipso = cipsov4;
 
 		ret_val = netlbl_af4list_add(&map->list, &addrmap->list4);
-		if (ret_val != 0) {
-			kfree(map);
-			goto add_free_addrmap;
-		}
+		if (ret_val != 0)
+			goto add_free_map;
 
 		entry->family = AF_INET;
 		entry->def.type = NETLBL_NLTYPE_ADDRSELECT;
 		entry->def.addrsel = addrmap;
+
 #if IS_ENABLED(CONFIG_IPV6)
 	} else if (info->attrs[NLBL_MGMT_A_IPV6ADDR]) {
 		struct in6_addr *addr;
@@ -223,6 +225,8 @@ static int netlbl_mgmt_add_common(struct genl_info *info,
 			ret_val = -ENOMEM;
 			goto add_free_addrmap;
 		}
+
+		pmap = map;
 		map->list.addr = *addr;
 		map->list.addr.s6_addr32[0] &= mask->s6_addr32[0];
 		map->list.addr.s6_addr32[1] &= mask->s6_addr32[1];
@@ -235,10 +239,8 @@ static int netlbl_mgmt_add_common(struct genl_info *info,
 			map->def.calipso = calipso;
 
 		ret_val = netlbl_af6list_add(&map->list, &addrmap->list6);
-		if (ret_val != 0) {
-			kfree(map);
-			goto add_free_addrmap;
-		}
+		if (ret_val != 0)
+			goto add_free_map;
 
 		entry->family = AF_INET6;
 		entry->def.type = NETLBL_NLTYPE_ADDRSELECT;
@@ -248,10 +250,12 @@ static int netlbl_mgmt_add_common(struct genl_info *info,
 
 	ret_val = netlbl_domhsh_add(entry, audit_info);
 	if (ret_val != 0)
-		goto add_free_addrmap;
+		goto add_free_map;
 
 	return 0;
 
+add_free_map:
+	kfree(pmap);
 add_free_addrmap:
 	kfree(addrmap);
 add_doi_put_def:
-- 
2.18.0.huawei.25