From b7d3d6df72a85552a4c6f3a8e5611a7847425314 Mon Sep 17 00:00:00 2001
From: Cong Wang <xiyou.wangcong@gmail.com>
Date: Fri, 24 Jul 2020 09:45:51 -0700
Subject: [PATCH] qrtr: orphan socket in qrtr_release()

[ Upstream commit af9f691f0f5bdd1ade65a7b84927639882d7c3e5 ]

We have to detach sock from socket in qrtr_release(),
otherwise skb->sk may still reference to this socket
when the skb is released in tun->queue, particularly
sk->sk_wq still points to &sock->wq, which leads to
a UAF.

Reported-and-tested-by: syzbot+6720d64f31c081c2f708@syzkaller.appspotmail.com
Fixes: 28fb4e59a47d ("net: qrtr: Expose tunneling endpoint to user space")
Cc: Bjorn Andersson <bjorn.andersson@linaro.org>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/qrtr/qrtr.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/qrtr/qrtr.c b/net/qrtr/qrtr.c
index 14c101e104ce..1ce1e710d025 100644
--- a/net/qrtr/qrtr.c
+++ b/net/qrtr/qrtr.c
@@ -1004,6 +1004,7 @@ static int qrtr_release(struct socket *sock)
 		sk->sk_state_change(sk);
 
 	sock_set_flag(sk, SOCK_DEAD);
+	sock_orphan(sk);
 	sock->sk = NULL;
 
 	if (!sock_flag(sk, SOCK_ZAPPED))