From c33b1cc62ac05c1dbb1cdafe2eb66da01c76ca8d Mon Sep 17 00:00:00 2001
From: Xiaoming Ni <nixiaoming@huawei.com>
Date: Thu, 25 Mar 2021 11:51:10 +0800
Subject: [PATCH] nfc: fix refcount leak in llcp_sock_bind()
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Git-commit: c33b1cc62ac05c1dbb1cdafe2eb66da01c76ca8d
Patch-mainline: v5.12-rc7
References: CVE-2020-25670 bsc#1178181

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>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 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;
-- 
2.26.2