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. Cc: <[email protected]> Signed-off-by: Takashi Iwai <[email protected]> --- drivers/bluetooth/hci_vhci.c | 22 ++++++++++++++++------ 1 file changed, 16 insertions(+), 6 deletions(-) diff --git a/drivers/bluetooth/hci_vhci.c b/drivers/bluetooth/hci_vhci.c index f67ea1c090cb..39230f30f544 100644 --- 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; }; @@ -87,7 +88,7 @@ static int vhci_send_frame(struct hci_dev *hdev, struct sk_buff *skb) return 0; } -static int vhci_create_device(struct vhci_data *data, __u8 opcode) +static int __vhci_create_device(struct vhci_data *data, __u8 opcode) { struct hci_dev *hdev; struct sk_buff *skb; @@ -151,6 +152,19 @@ static int vhci_create_device(struct vhci_data *data, __u8 opcode) return 0; } +static int vhci_create_device(struct vhci_data *data, __u8 opcode) +{ + int err; + + mutex_lock(&data->open_mutex); + if (data->hdev) + err = -EBADFD; + else + err = __vhci_create_device(data, opcode); + mutex_unlock(&data->open_mutex); + return err; +} + static inline ssize_t vhci_get_user(struct vhci_data *data, struct iov_iter *from) { @@ -191,11 +205,6 @@ static inline ssize_t vhci_get_user(struct vhci_data *data, case HCI_VENDOR_PKT: cancel_delayed_work_sync(&data->open_timeout); - if (data->hdev) { - kfree_skb(skb); - return -EBADFD; - } - opcode = *((__u8 *) skb->data); skb_pull(skb, 1); @@ -320,6 +329,7 @@ static int vhci_open(struct inode *inode, struct file *file) 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; -- 2.8.1
