vsock: prevent unnecessary refcnt inc for nonblocking connect

stable inclusion
from stable-5.10.80
commit 7e03b797bee0b9da2d329c3edbc6937062f01215
bugzilla: 185821 https://gitee.com/openeuler/kernel/issues/I4L7CG

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=7e03b797bee0b9da2d329c3edbc6937062f01215

--------------------------------

[ Upstream commit c7cd82b9 ]

Currently vosck_connect() increments sock refcount for nonblocking
socket each time it's called, which can lead to memory leak if
it's called multiple times because connect timeout function decrements
sock refcount only once.

Fixes it by making vsock_connect() return -EALREADY immediately when
sock state is already SS_CONNECTING.

Fixes: d021c344 ("VSOCK: Introduce VM Sockets")
Reviewed-by: NStefano Garzarella <sgarzare@redhat.com>
Signed-off-by: NEiichi Tsukata <eiichi.tsukata@nutanix.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Reviewed-by: NWeilong Chen <chenweilong@huawei.com>
Acked-by: NWeilong Chen <chenweilong@huawei.com>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

net/vmw_vsock/af_vsock.c

@@ -1279,6 +1279,8 @@ static int vsock_stream_connect(struct socket *sock, struct sockaddr *addr,
 		 * non-blocking call.
 		 */
 		err = -EALREADY;
+		if (flags & O_NONBLOCK)
+			goto out;
 		break;
 	default:
 		if ((sk->sk_state == TCP_LISTEN) ||