linux-kernel - [PATCH 4.4 03/38] nfc: fix refcount leak in llcp_sock

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Date:   Thu, 15 Apr 2021 16:46:57 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, =?UTF-8?q?kiyin ?= <kiyin@...cent.com>,
        Xiaoming Ni <nixiaoming@...wei.com>,
        "David S. Miller" <davem@...emloft.net>
Subject: [PATCH 4.4 03/38] nfc: fix refcount leak in llcp_sock_bind()

From: Xiaoming Ni <nixiaoming@...wei.com>

commit c33b1cc62ac05c1dbb1cdafe2eb66da01c76ca8d upstream.

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@...cent.com>
Link: https://www.openwall.com/lists/oss-security/2020/11/01/1
Cc: <stable@...r.kernel.org> #v3.6
Signed-off-by: Xiaoming Ni <nixiaoming@...wei.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 net/nfc/llcp_sock.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/net/nfc/llcp_sock.c
+++ b/net/nfc/llcp_sock.c
@@ -119,11 +119,13 @@ static int llcp_sock_bind(struct socket
 					  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;