netdev - [PATCH resend 1/4] nfc: fix refcount leak in llcp_sock

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Date:   Thu, 25 Mar 2021 11:51:10 +0800
From:   Xiaoming Ni <nixiaoming@...wei.com>
To:     <linux-kernel@...r.kernel.org>, <kiyin@...cent.com>,
        <stable@...r.kernel.org>, <gregkh@...uxfoundation.org>,
        <sameo@...ux.intel.com>, <linville@...driver.com>,
        <davem@...emloft.net>, <kuba@...nel.org>, <mkl@...gutronix.de>,
        <stefan@...enfreihafen.org>, <matthieu.baerts@...sares.net>,
        <netdev@...r.kernel.org>
CC:     <nixiaoming@...wei.com>, <wangle6@...wei.com>,
        <xiaoqian9@...wei.com>
Subject: [PATCH resend 1/4] 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@...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>
---
 net/nfc/llcp_sock.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/nfc/llcp_sock.c b/net/nfc/llcp_sock.c
index d257ed3b732a..68832ee4b9f8 100644
--- 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;
-- 
2.27.0