[3.19.y-ckt stable] Patch "Bluetooth: vhci: Fix race at creating hci device" has been added to the 3.19.y-ckt tree

Kamal Mostafa kamal at canonical.com
Wed Jul 6 21:00:10 UTC 2016


This is a note to let you know that I have just added a patch titled

    Bluetooth: vhci: Fix race at creating hci device

to the linux-3.19.y-queue branch of the 3.19.y-ckt extended stable tree 
which can be found at:

    https://git.launchpad.net/~canonical-kernel/linux/+git/linux-stable-ckt/log/?h=linux-3.19.y-queue

This patch is scheduled to be released in version 3.19.8-ckt23.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.19.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

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

>From 45e5d9361c8364aa7c32005ed102944f7fb7bb85 Mon Sep 17 00:00:00 2001
From: Takashi Iwai <tiwai at suse.de>
Date: Thu, 14 Apr 2016 17:32:19 +0200
Subject: Bluetooth: vhci: Fix race at creating hci device

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 at suse.de>
Signed-off-by: Marcel Holtmann <marcel at holtmann.org>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 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 5b9ac12..eaa646d 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





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