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Bluetooth: Fix double free in hci_conn_cleanup

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[ Upstream commit a85fb91e3d728bdfc80833167e8162cce8bc7004 ]

syzbot reports a slab use-after-free in hci_conn_hash_flush [1].
After releasing an object using hci_conn_del_sysfs in the
hci_conn_cleanup function, releasing the same object again
using the hci_dev_put and hci_conn_put functions causes a double free.
Here's a simplified flow:

hci_conn_del_sysfs:
  hci_dev_put
    put_device
      kobject_put
        kref_put
          kobject_release
            kobject_cleanup
              kfree_const
                kfree(name)

hci_dev_put:
  ...
    kfree(name)

hci_conn_put:
  put_device
    ...
      kfree(name)

This patch drop the hci_dev_put and hci_conn_put function
call in hci_conn_cleanup function, because the object is
freed in hci_conn_del_sysfs function.

This patch also fixes the refcounting in hci_conn_add_sysfs() and
hci_conn_del_sysfs() to take into account device_add() failures.

This fixes CVE-2023-28464.

Link: https://syzkaller.appspot.com/bug?id=1bb51491ca5df96a5f724899d1dbb87afda61419 [1]

Signed-off-by: ZhengHan Wang <wzhmmmmm@gmail.com>
Co-developed-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
ZhengHan Wang 2023-10-18 12:30:55 +02:00 committed by Greg Kroah-Hartman
parent 3cf391e417
commit 3c4236f1b2
2 changed files with 14 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
net/bluetooth/hci_conn.c
View File

@ -125,13 +125,11 @@ static void hci_conn_cleanup(struct hci_conn *conn)
if (hdev->notify) if (hdev->notify)
hdev->notify(hdev, HCI_NOTIFY_CONN_DEL); hdev->notify(hdev, HCI_NOTIFY_CONN_DEL);
hci_conn_del_sysfs(conn);
debugfs_remove_recursive(conn->debugfs); debugfs_remove_recursive(conn->debugfs);
hci_dev_put(hdev); hci_conn_del_sysfs(conn);
hci_conn_put(conn); hci_dev_put(hdev);
} }
static void le_scan_cleanup(struct work_struct *work) static void le_scan_cleanup(struct work_struct *work)

23
net/bluetooth/hci_sysfs.c
View File

@ -33,7 +33,7 @@ void hci_conn_init_sysfs(struct hci_conn *conn)
{ {
struct hci_dev *hdev = conn->hdev; struct hci_dev *hdev = conn->hdev;
BT_DBG("conn %p", conn); bt_dev_dbg(hdev, "conn %p", conn);
conn->dev.type = &bt_link; conn->dev.type = &bt_link;
conn->dev.class = bt_class; conn->dev.class = bt_class;
@ -46,27 +46,30 @@ void hci_conn_add_sysfs(struct hci_conn *conn)
{ {
struct hci_dev *hdev = conn->hdev; struct hci_dev *hdev = conn->hdev;
BT_DBG("conn %p", conn); bt_dev_dbg(hdev, "conn %p", conn);
if (device_is_registered(&conn->dev)) if (device_is_registered(&conn->dev))
return; return;
dev_set_name(&conn->dev, "%s:%d", hdev->name, conn->handle); dev_set_name(&conn->dev, "%s:%d", hdev->name, conn->handle);
if (device_add(&conn->dev) < 0) { if (device_add(&conn->dev) < 0)
bt_dev_err(hdev, "failed to register connection device"); bt_dev_err(hdev, "failed to register connection device");
return;
}
hci_dev_hold(hdev);
} }
void hci_conn_del_sysfs(struct hci_conn *conn) void hci_conn_del_sysfs(struct hci_conn *conn)
{ {
struct hci_dev *hdev = conn->hdev; struct hci_dev *hdev = conn->hdev;
if (!device_is_registered(&conn->dev)) bt_dev_dbg(hdev, "conn %p", conn);
if (!device_is_registered(&conn->dev)) {
/* If device_add() has *not* succeeded, use *only* put_device()
* to drop the reference count.
*/
put_device(&conn->dev);
return; return;
}
while (1) { while (1) {
struct device *dev; struct device *dev;
@ -78,9 +81,7 @@ void hci_conn_del_sysfs(struct hci_conn *conn)
put_device(dev); put_device(dev);
} }
device_del(&conn->dev); device_unregister(&conn->dev);
hci_dev_put(hdev);
} }
static void bt_host_release(struct device *dev) static void bt_host_release(struct device *dev)