[PATCH] Bluetooth: fix the erroneous flush_work() order

[PATCH] Bluetooth: fix the erroneous flush_work() order

[Greg Kroah-Hartman]

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

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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/bluetooth/hci_core.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
index fd12f1652bdf..88aa32f44e68 100644
--- a/net/bluetooth/hci_core.c
+++ b/net/bluetooth/hci_core.c
@@ -1610,8 +1610,13 @@ static int hci_dev_do_open(struct hci_dev *hdev)
 	} 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);
-- 
2.31.1

Re: [PATCH] Bluetooth: fix the erroneous flush_work() order

[Marcel Holtmann]

Hi Greg,

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

this needs a real name, but I could fix that on git am as well.

> 
> 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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> ---
> net/bluetooth/hci_core.c | 7 ++++++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
> index fd12f1652bdf..88aa32f44e68 100644
> --- a/net/bluetooth/hci_core.c
> +++ b/net/bluetooth/hci_core.c
> @@ -1610,8 +1610,13 @@ static int hci_dev_do_open(struct hci_dev *hdev)
> 	} 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()
> +		 */

So everything in net/ uses the comment coding style enforced with --strict.

Regards

Marcel

Re: [PATCH] Bluetooth: fix the erroneous flush_work() order

[Greg Kroah-Hartman]

On Wed, May 26, 2021 at 05:05:50PM +0200, Marcel Holtmann wrote:
> Hi Greg,
> 
> > From: linma <linma@zju.edu.cn>
> 
> this needs a real name, but I could fix that on git am as well.

"Lin Ma"

> > 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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> > ---
> > net/bluetooth/hci_core.c | 7 ++++++-
> > 1 file changed, 6 insertions(+), 1 deletion(-)
> > 
> > diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
> > index fd12f1652bdf..88aa32f44e68 100644
> > --- a/net/bluetooth/hci_core.c
> > +++ b/net/bluetooth/hci_core.c
> > @@ -1610,8 +1610,13 @@ static int hci_dev_do_open(struct hci_dev *hdev)
> > 	} 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()
> > +		 */
> 
> So everything in net/ uses the comment coding style enforced with --strict.

See v2 please.

thanks,

greg k-h