From: Xiaoming Ni <nixiaoming@huawei.com>
Date: Thu, 25 Mar 2021 03:51:13 +0000 (+0800)
Subject: nfc: Avoid endless loops caused by repeated llcp_sock_connect()
X-Git-Tag: v4.4.267~33
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=7f6c9e4314aa7d90b6261b8ae571d14c454ba964;p=thirdparty%2Fkernel%2Fstable.git

nfc: Avoid endless loops caused by repeated llcp_sock_connect()

commit 4b5db93e7f2afbdfe3b78e37879a85290187e6f1 upstream.

When sock_wait_state() returns -EINPROGRESS, "sk->sk_state" is
 LLCP_CONNECTING. In this case, llcp_sock_connect() is repeatedly invoked,
 nfc_llcp_sock_link() will add sk to local->connecting_sockets twice.
 sk->sk_node->next will point to itself, that will make an endless loop
 and hang-up the system.
To fix it, check whether sk->sk_state is LLCP_CONNECTING in
 llcp_sock_connect() to avoid repeated invoking.

Fixes: b4011239a08e ("NFC: llcp: Fix non blocking sockets connections")
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> #v3.11
Signed-off-by: Xiaoming Ni <nixiaoming@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/net/nfc/llcp_sock.c b/net/nfc/llcp_sock.c
index 7632593975449..2f8d38d0802ac 100644
--- a/net/nfc/llcp_sock.c
+++ b/net/nfc/llcp_sock.c
@@ -679,6 +679,10 @@ static int llcp_sock_connect(struct socket *sock, struct sockaddr *_addr,
 		ret = -EISCONN;
 		goto error;
 	}
+	if (sk->sk_state == LLCP_CONNECTING) {
+		ret = -EINPROGRESS;
+		goto error;
+	}
 
 	dev = nfc_get_device(addr->dev_idx);
 	if (dev == NULL) {