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    Subject[PATCH 3.16 021/305] Bluetooth: vhci: Fix race at creating hci device
    3.16.37-rc1 review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Takashi Iwai <tiwai@suse.de>

    commit c7c999cb18da88a881e10e07f0724ad0bfaff770 upstream.

    hci_vhci driver creates a hci device object dynamically upon each
    HCI_VENDOR_PKT write. Although it checks the already created object
    and returns an error, it's still racy and may build multiple hci_dev
    objects concurrently when parallel writes are performed, as the device
    tracks only a single hci_dev object.

    This patch introduces a mutex to protect against the concurrent device
    creations.

    Signed-off-by: Takashi Iwai <tiwai@suse.de>
    Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
    [bwh: Backported to 3.16: adjust context]
    Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
    ---
    drivers/bluetooth/hci_vhci.c | 23 +++++++++++++++++------
    1 file changed, 17 insertions(+), 6 deletions(-)

    --- a/drivers/bluetooth/hci_vhci.c
    +++ b/drivers/bluetooth/hci_vhci.c
    @@ -50,6 +50,7 @@ struct vhci_data {
    wait_queue_head_t read_wait;
    struct sk_buff_head readq;

    + struct mutex open_mutex;
    struct delayed_work open_timeout;
    };

    @@ -95,11 +96,14 @@ static int vhci_send_frame(struct hci_de
    return 0;
    }

    -static int vhci_create_device(struct vhci_data *data, __u8 dev_type)
    +static int __vhci_create_device(struct vhci_data *data, __u8 dev_type)
    {
    struct hci_dev *hdev;
    struct sk_buff *skb;

    + if (data->hdev)
    + return -EBADFD;
    +
    skb = bt_skb_alloc(4, GFP_KERNEL);
    if (!skb)
    return -ENOMEM;
    @@ -140,6 +144,17 @@ static int vhci_create_device(struct vhc
    return 0;
    }

    +static int vhci_create_device(struct vhci_data *data, __u8 opcode)
    +{
    + int err;
    +
    + mutex_lock(&data->open_mutex);
    + err = __vhci_create_device(data, opcode);
    + mutex_unlock(&data->open_mutex);
    +
    + return err;
    +}
    +
    static inline ssize_t vhci_get_user(struct vhci_data *data,
    const struct iovec *iov,
    unsigned long count)
    @@ -185,11 +200,6 @@ static inline ssize_t vhci_get_user(stru
    case HCI_VENDOR_PKT:
    cancel_delayed_work_sync(&data->open_timeout);

    - if (data->hdev) {
    - kfree_skb(skb);
    - return -EBADFD;
    - }
    -
    dev_type = *((__u8 *) skb->data);
    skb_pull(skb, 1);

    @@ -318,6 +328,7 @@ static int vhci_open(struct inode *inode
    skb_queue_head_init(&data->readq);
    init_waitqueue_head(&data->read_wait);

    + mutex_init(&data->open_mutex);
    INIT_DELAYED_WORK(&data->open_timeout, vhci_open_timeout);

    file->private_data = data;
    \
     
     \ /
      Last update: 2016-09-17 09:56    [W:2.577 / U:0.108 seconds]
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