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References: <20230222000915.2843208-1-jiangzp@google.com> <20230221160910.kernel.v1.1.If0578b001c1f12567f2ebcac5856507f1adee745@changeid>
In-Reply-To: <20230221160910.kernel.v1.1.If0578b001c1f12567f2ebcac5856507f1adee745@changeid>
From:   Zhengping Jiang <jiangzp@google.com>
Date:   Wed, 22 Feb 2023 10:44:09 -0800
Message-ID: <CAB4PzUp327-efiARXhsE6Ep+1Lf2T501CexBqhWAhPzMQiEYVQ@mail.gmail.com>
Subject: Re: [kernel PATCH v1 1/1] Bluetooth: hci_sync: clear workqueue before
 clear mgmt cmd
To:     linux-bluetooth@vger.kernel.org, marcel@holtmann.org,
        luiz.dentz@gmail.com
Cc:     chromeos-bluetooth-upstreaming@chromium.org, mmandlik@google.com,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Johan Hedberg <johan.hedberg@gmail.com>,
        Paolo Abeni <pabeni@redhat.com>, linux-kernel@vger.kernel.org,
        netdev@vger.kernel.org
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

Hi,

We need to revise this patch after a local test failure. I will update
after finding the cause.

Thanks,
Zhengping

On Tue, Feb 21, 2023 at 4:09 PM Zhengping Jiang <jiangzp@google.com> wrote:
>
> Clear cmd_sync_work queue before clearing the mgmt cmd list to avoid
> racing conditions which cause use-after-free.
>
> When powering off the adapter, the mgmt cmd list will be cleared. If a
> work is queued in the cmd_sync_work queue at the same time, it will
> cause the risk of use-after-free, as the cmd pointer is not checked
> before use.
>
> Signed-off-by: Zhengping Jiang <jiangzp@google.com>
> ---
>
> Changes in v1:
> - Clear cmd_sync_work queue before clearing the mgmt cmd list
>
>  net/bluetooth/hci_sync.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/net/bluetooth/hci_sync.c b/net/bluetooth/hci_sync.c
> index 117eedb6f709..6609434e3125 100644
> --- a/net/bluetooth/hci_sync.c
> +++ b/net/bluetooth/hci_sync.c
> @@ -4840,6 +4840,8 @@ int hci_dev_close_sync(struct hci_dev *hdev)
>
>         auto_off = hci_dev_test_and_clear_flag(hdev, HCI_AUTO_OFF);
>
> +       hci_cmd_sync_clear(hdev);
> +
>         if (!auto_off && hdev->dev_type == HCI_PRIMARY &&
>             !hci_dev_test_flag(hdev, HCI_USER_CHANNEL) &&
>             hci_dev_test_flag(hdev, HCI_MGMT))
> --
> 2.39.2.637.g21b0678d19-goog
>