linux-kernel - Re: [PATCH] Bluetooth: fix the erroneous flush

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Message-Id: <87CD8C35-C7D2-4CF7-B9F9-266B3498DB94@holtmann.org>
Date:   Wed, 26 May 2021 17:05:50 +0200
From:   Marcel Holtmann <marcel@...tmann.org>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Johan Hedberg <johan.hedberg@...il.com>,
        Luiz Augusto von Dentz <luiz.dentz@...il.com>,
        linma <linma@....edu.cn>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        linux-bluetooth@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, Hao Xiong <mart1n@....edu.cn>,
        stable <stable@...r.kernel.org>
Subject: Re: [PATCH] Bluetooth: fix the erroneous flush_work() order

Hi Greg,

> From: linma <linma@....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@...tmann.org>
> Cc: Johan Hedberg <johan.hedberg@...il.com>
> Cc: Luiz Augusto von Dentz <luiz.dentz@...il.com>
> Cc: "David S. Miller" <davem@...emloft.net>
> Cc: Jakub Kicinski <kuba@...nel.org>
> Cc: linux-bluetooth@...r.kernel.org
> Cc: netdev@...r.kernel.org
> Cc: linux-kernel@...r.kernel.org
> Signed-off-by: Lin Ma <linma@....edu.cn>
> Signed-off-by: Hao Xiong <mart1n@....edu.cn>
> Cc: stable <stable@...r.kernel.org>
> Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.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