[PATCH 4.2.y-ckt 025/206] Bluetooth: vhci: Fix race at creating hci device

From: Kamal Mostafa
Date: Thu Jun 09 2016 - 18:15:50 EST


4.2.8-ckt12 -stable review patch. If anyone has any objections, please let me know.

---8<------------------------------------------------------------

From: Takashi Iwai <tiwai@xxxxxxx>

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@xxxxxxx>
Signed-off-by: Marcel Holtmann <marcel@xxxxxxxxxxxx>
Signed-off-by: Kamal Mostafa <kamal@xxxxxxxxxxxxx>
---
drivers/bluetooth/hci_vhci.c | 23 +++++++++++++++++------
1 file changed, 17 insertions(+), 6 deletions(-)

diff --git a/drivers/bluetooth/hci_vhci.c b/drivers/bluetooth/hci_vhci.c
index a269b34..4c4aa7d 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;
};

@@ -95,12 +96,15 @@ 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;
__u8 dev_type;

+ if (data->hdev)
+ return -EBADFD;
+
/* bits 0-1 are dev_type (BR/EDR or AMP) */
dev_type = opcode & 0x03;

@@ -159,6 +163,17 @@ 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);
+ 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)
{
@@ -199,11 +214,6 @@ 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);

@@ -328,6 +338,7 @@ 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;
--
2.7.4