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

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

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