Bluetooth: prefetch channel before killing sock
Prefetch channel before killing sock in order to fix UAF like
BUG: KASAN: use-after-free in l2cap_sock_release+0x24c/0x290 net/bluetooth/l2cap_sock.c:1212
Read of size 8 at addr ffff8880944904a0 by task syz-fuzzer/9751
Reported-by: syzbot+c3c5bdea7863886115dc@syzkaller.appspotmail.com
Fixes: 6c08fc896b
("Bluetooth: Fix refcount use-after-free issue")
Cc: Manish Mandlik <mmandlik@google.com>
Signed-off-by: Hillf Danton <hdanton@sina.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
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@ -1193,6 +1193,7 @@ static int l2cap_sock_release(struct socket *sock)
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{
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struct sock *sk = sock->sk;
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int err;
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struct l2cap_chan *chan;
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BT_DBG("sock %p, sk %p", sock, sk);
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@ -1202,15 +1203,16 @@ static int l2cap_sock_release(struct socket *sock)
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bt_sock_unlink(&l2cap_sk_list, sk);
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err = l2cap_sock_shutdown(sock, 2);
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chan = l2cap_pi(sk)->chan;
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l2cap_chan_hold(l2cap_pi(sk)->chan);
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l2cap_chan_lock(l2cap_pi(sk)->chan);
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l2cap_chan_hold(chan);
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l2cap_chan_lock(chan);
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sock_orphan(sk);
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l2cap_sock_kill(sk);
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l2cap_chan_unlock(l2cap_pi(sk)->chan);
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l2cap_chan_put(l2cap_pi(sk)->chan);
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l2cap_chan_unlock(chan);
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l2cap_chan_put(chan);
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return err;
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}
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