nfc: fix refcount leak in llcp_sock_connect()

nfc_llcp_local_get() is invoked in llcp_sock_connect(),
but nfc_llcp_local_put() is not invoked in subsequent failure branches.
As a result, refcount leakage occurs.
To fix it, add calling nfc_llcp_local_put().

fix CVE-2020-25671
Fixes: c7aa12252f51 ("NFC: Take a reference on the LLCP local pointer when creating a socket")
Reported-by: "kiyin(尹亮)" <kiyin@tencent.com>
Link: https://www.openwall.com/lists/oss-security/2020/11/01/1
Cc: <stable@vger.kernel.org> #v3.6
Signed-off-by: Xiaoming Ni <nixiaoming@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/nfc/llcp_sock.c b/net/nfc/llcp_sock.c
index 68832ee..9e2799e 100644 (file)
--- a/net/nfc/llcp_sock.c
+++ b/net/nfc/llcp_sock.c
@@ -704,6 +704,7 @@ static int llcp_sock_connect(struct socket *sock, struct sockaddr *_addr,
        llcp_sock->local = nfc_llcp_local_get(local);
        llcp_sock->ssap = nfc_llcp_get_local_ssap(local);
        if (llcp_sock->ssap == LLCP_SAP_MAX) {
+               nfc_llcp_local_put(llcp_sock->local);
                ret = -ENOMEM;
                goto put_dev;
        }
@@ -748,6 +749,7 @@ sock_unlink:
 
 sock_llcp_release:
        nfc_llcp_put_ssap(local, llcp_sock->ssap);
+       nfc_llcp_local_put(llcp_sock->local);
 
 put_dev:
        nfc_put_device(dev);