From: Hyunwoo Kim imv4bel@gmail.com
commit 5610bcfe8693c02e2e4c8b31427f1bdbdecc839c upstream.
A race condition may occur if the user physically removes the USB device while calling open() for this device node.
This is a race condition between the ufx_ops_open() function and the ufx_usb_disconnect() function, which may eventually result in UAF.
So, add a mutex to the ufx_ops_open() and ufx_usb_disconnect() functions to avoid race contidion of krefs.
Signed-off-by: Hyunwoo Kim imv4bel@gmail.com Cc: stable@vger.kernel.org Signed-off-by: Helge Deller deller@gmx.de Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/video/fbdev/smscufx.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-)
--- a/drivers/video/fbdev/smscufx.c +++ b/drivers/video/fbdev/smscufx.c @@ -140,6 +140,8 @@ static int ufx_submit_urb(struct ufx_dat static int ufx_alloc_urb_list(struct ufx_data *dev, int count, size_t size); static void ufx_free_urb_list(struct ufx_data *dev);
+static DEFINE_MUTEX(disconnect_mutex); + /* reads a control register */ static int ufx_reg_read(struct ufx_data *dev, u32 index, u32 *data) { @@ -1073,9 +1075,13 @@ static int ufx_ops_open(struct fb_info * if (user == 0 && !console) return -EBUSY;
+ mutex_lock(&disconnect_mutex); + /* If the USB device is gone, we don't accept new opens */ - if (dev->virtualized) + if (dev->virtualized) { + mutex_unlock(&disconnect_mutex); return -ENODEV; + }
dev->fb_count++;
@@ -1100,6 +1106,8 @@ static int ufx_ops_open(struct fb_info * pr_debug("open /dev/fb%d user=%d fb_info=%p count=%d", info->node, user, info, dev->fb_count);
+ mutex_unlock(&disconnect_mutex); + return 0; }
@@ -1762,6 +1770,8 @@ static void ufx_usb_disconnect(struct us { struct ufx_data *dev;
+ mutex_lock(&disconnect_mutex); + dev = usb_get_intfdata(interface);
pr_debug("USB disconnect starting\n"); @@ -1782,6 +1792,8 @@ static void ufx_usb_disconnect(struct us kref_put(&dev->kref, ufx_free);
/* consider ufx_data freed */ + + mutex_unlock(&disconnect_mutex); }
static struct usb_driver ufx_driver = {