netdev - [Patch net v2] qrtr: orphan socket in qrtr

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Date:   Fri, 24 Jul 2020 09:45:51 -0700
From:   Cong Wang <xiyou.wangcong@...il.com>
To:     netdev@...r.kernel.org
Cc:     Cong Wang <xiyou.wangcong@...il.com>,
        syzbot+6720d64f31c081c2f708@...kaller.appspotmail.com,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Eric Dumazet <eric.dumazet@...il.com>
Subject: [Patch net v2] qrtr: orphan socket in qrtr_release()

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@...kaller.appspotmail.com
Fixes: 28fb4e59a47d ("net: qrtr: Expose tunneling endpoint to user space")
Cc: Bjorn Andersson <bjorn.andersson@...aro.org>
Cc: Eric Dumazet <eric.dumazet@...il.com>
Signed-off-by: Cong Wang <xiyou.wangcong@...il.com>
---
 net/qrtr/qrtr.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/qrtr/qrtr.c b/net/qrtr/qrtr.c
index 24a8c3c6da0d..300a104b9a0f 100644
--- a/net/qrtr/qrtr.c
+++ b/net/qrtr/qrtr.c
@@ -1180,6 +1180,7 @@ 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))
-- 
2.27.0