[PATCH 4.9 13/29] Bluetooth: fix the erroneous flush_work() order

Greg Kroah-Hartman
2021-06-08T18:31:55Z

From: Lin Ma <linma@zju.edu.cn>

commit 6a137caec23aeb9e036cdfd8a46dd8a366460e5d upstream.

In the cleanup routine for failed initialization of HCI device,
the flush_work(&hdev->rx_work) need to be finished before the
flush_work(&hdev->cmd_work). Otherwise, the hci_rx_work() can
possibly invoke new cmd_work and cause a bug, like double free,
in late processings.

This was assigned CVE-2021-3564.

This patch reorder the flush_work() to fix this bug.

Cc: Marcel Holtmann <marcel@holtmann.org>
Cc: Johan Hedberg <johan.hedberg@gmail.com>
Cc: Luiz Augusto von Dentz <luiz.dentz@gmail.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: linux-bluetooth@vger.kernel.org
Cc: netdev@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Lin Ma <linma@zju.edu.cn>
Signed-off-by: Hao Xiong <mart1n@zju.edu.cn>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/bluetooth/hci_core.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)

--- a/net/bluetooth/hci_core.c
+++ b/net/bluetooth/hci_core.c
@@ -1422,8 +1422,13 @@ static int hci_dev_do_open(struct hci_de
} else {
/* Init failed, cleanup */
flush_work(&hdev->tx_work);
- flush_work(&hdev->cmd_work);
+
+ /* Since hci_rx_work() is possible to awake new cmd_work
+ * it should be flushed first to avoid unexpected call of
+ * hci_cmd_work()
+ */
flush_work(&hdev->rx_work);
+ flush_work(&hdev->cmd_work);

skb_queue_purge(&hdev->cmd_q);
skb_queue_purge(&hdev->rx_q);