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Bluetooth: Refcnt drop must be placed last in hci_conn_unlink
If hci_conn_put(conn->parent) reduces conn->parent's reference count to
zero, it can immediately deallocate conn->parent. At the same time,
conn->link->list has its head in conn->parent, causing use-after-free
problems in the latter list_del_rcu(&conn->link->list).
This problem can be easily solved by reordering the two operations,
i.e., first performing the list removal with list_del_rcu and then
decreasing the refcnt with hci_conn_put.
Reported-by: Luiz Augusto von Dentz <luiz.dentz@gmail.com>
Closes: https://lore.kernel.org/linux-bluetooth/CABBYNZ+1kce8_RJrLNOXd_8=Mdpb=2bx4Nto-hFORk=qiOkoCg@mail.gmail.com/
Fixes: 06149746e7
("Bluetooth: hci_conn: Add support for linking multiple hcon")
Signed-off-by: Ruihan Li <lrh2000@pku.edu.cn>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
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@ -1102,12 +1102,12 @@ static void hci_conn_unlink(struct hci_conn *conn)
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if (!conn->link)
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return;
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hci_conn_put(conn->parent);
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conn->parent = NULL;
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list_del_rcu(&conn->link->list);
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synchronize_rcu();
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hci_conn_put(conn->parent);
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conn->parent = NULL;
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kfree(conn->link);
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conn->link = NULL;
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}
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