[PATCH 4.4 04/38] nfc: fix refcount leak in llcp_sock_connect()

[Greg Kroah-Hartman]

From: Xiaoming Ni <nixiaom...@huawei.com>

commit 8a4cd82d62b5ec7e5482333a72b58a4eea4979f0 upstream.

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)" <ki...@tencent.com>
Link: https://www.openwall.com/lists/oss-security/2020/11/01/1
Cc: <sta...@vger.kernel.org> #v3.6
Signed-off-by: Xiaoming Ni <nixiaom...@huawei.com>
Signed-off-by: David S. Miller <da...@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
 net/nfc/llcp_sock.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/net/nfc/llcp_sock.c
+++ b/net/nfc/llcp_sock.c
@@ -710,6 +710,7 @@ static int llcp_sock_connect(struct sock
        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;
        }
@@ -747,6 +748,7 @@ static int llcp_sock_connect(struct sock
 
 sock_unlink:
        nfc_llcp_put_ssap(local, llcp_sock->ssap);
+       nfc_llcp_local_put(llcp_sock->local);
 
        nfc_llcp_sock_unlink(&local->connecting_sockets, sk);