releases/4.6.1/bluetooth-vhci-fix-race-at-creating-hci-device.patch

   1 From c7c999cb18da88a881e10e07f0724ad0bfaff770 Mon Sep 17 00:00:00 2001
   2 From: Takashi Iwai <tiwai@suse.de>
   3 Date: Thu, 14 Apr 2016 17:32:19 +0200
   4 Subject: Bluetooth: vhci: Fix race at creating hci device
   5
   6 From: Takashi Iwai <tiwai@suse.de>
   7
   8 commit c7c999cb18da88a881e10e07f0724ad0bfaff770 upstream.
   9
  10 hci_vhci driver creates a hci device object dynamically upon each
  11 HCI_VENDOR_PKT write.  Although it checks the already created object
  12 and returns an error, it's still racy and may build multiple hci_dev
  13 objects concurrently when parallel writes are performed, as the device
  14 tracks only a single hci_dev object.
  15
  16 This patch introduces a mutex to protect against the concurrent device
  17 creations.
  18
  19 Signed-off-by: Takashi Iwai <tiwai@suse.de>
  20 Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
  21 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  22
  23 ---
  24  drivers/bluetooth/hci_vhci.c |   23 +++++++++++++++++------
  25  1 file changed, 17 insertions(+), 6 deletions(-)
  26
  27 --- a/drivers/bluetooth/hci_vhci.c
  28 +++ b/drivers/bluetooth/hci_vhci.c
  29 @@ -50,6 +50,7 @@ struct vhci_data {
  30         wait_queue_head_t read_wait;
  31         struct sk_buff_head readq;
  32
  33 +       struct mutex open_mutex;
  34         struct delayed_work open_timeout;
  35  };
  36
  37 @@ -87,12 +88,15 @@ static int vhci_send_frame(struct hci_de
  38         return 0;
  39  }
  40
  41 -static int vhci_create_device(struct vhci_data *data, __u8 opcode)
  42 +static int __vhci_create_device(struct vhci_data *data, __u8 opcode)
  43  {
  44         struct hci_dev *hdev;
  45         struct sk_buff *skb;
  46         __u8 dev_type;
  47
  48 +       if (data->hdev)
  49 +               return -EBADFD;
  50 +
  51         /* bits 0-1 are dev_type (BR/EDR or AMP) */
  52         dev_type = opcode & 0x03;
  53
  54 @@ -151,6 +155,17 @@ static int vhci_create_device(struct vhc
  55         return 0;
  56  }
  57
  58 +static int vhci_create_device(struct vhci_data *data, __u8 opcode)
  59 +{
  60 +       int err;
  61 +
  62 +       mutex_lock(&data->open_mutex);
  63 +       err = __vhci_create_device(data, opcode);
  64 +       mutex_unlock(&data->open_mutex);
  65 +
  66 +       return err;
  67 +}
  68 +
  69  static inline ssize_t vhci_get_user(struct vhci_data *data,
  70                                     struct iov_iter *from)
  71  {
  72 @@ -191,11 +206,6 @@ static inline ssize_t vhci_get_user(stru
  73         case HCI_VENDOR_PKT:
  74                 cancel_delayed_work_sync(&data->open_timeout);
  75
  76 -               if (data->hdev) {
  77 -                       kfree_skb(skb);
  78 -                       return -EBADFD;
  79 -               }
  80 -
  81                 opcode = *((__u8 *) skb->data);
  82                 skb_pull(skb, 1);
  83
  84 @@ -320,6 +330,7 @@ static int vhci_open(struct inode *inode
  85         skb_queue_head_init(&data->readq);
  86         init_waitqueue_head(&data->read_wait);
  87
  88 +       mutex_init(&data->open_mutex);
  89         INIT_DELAYED_WORK(&data->open_timeout, vhci_open_timeout);
  90
  91         file->private_data = data;