nfc: fix refcount leak in llcp_sock_bind()

nfc_llcp_local_get() is invoked in llcp_sock_bind(),
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-2020-25670
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 d257ed3..68832ee 100644 (file)
--- a/net/nfc/llcp_sock.c
+++ b/net/nfc/llcp_sock.c
@@ -108,11 +108,13 @@ static int llcp_sock_bind(struct socket *sock, struct sockaddr *addr, int alen)
                                          llcp_sock->service_name_len,
                                          GFP_KERNEL);
        if (!llcp_sock->service_name) {
+               nfc_llcp_local_put(llcp_sock->local);
                ret = -ENOMEM;
                goto put_dev;
        }
        llcp_sock->ssap = nfc_llcp_get_sdp_ssap(local, llcp_sock);
        if (llcp_sock->ssap == LLCP_SAP_MAX) {
+               nfc_llcp_local_put(llcp_sock->local);
                kfree(llcp_sock->service_name);
                llcp_sock->service_name = NULL;
                ret = -EADDRINUSE;