lk/linux-kernel-test
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

USB: usb-skeleton.c: fix open/disconnect race

Browse Source 
If usb device is disconnected between usb_get_intfdata()
and kref_get() in skel_open(), kref_get may access a freed
object.

Also check if device is disconnected in ->open.

Signed-off-by: Ming Lei <tom.leiming@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Ming Lei
2011-12-16 22:20:01 +08:00
committed by Greg Kroah-Hartman
parent e78832cdca
commit 26c71a79ca
1 changed files with 17 additions and 1 deletions
Download Patch File Download Diff File Expand all files Collapse all files

18
drivers/usb/usb-skeleton.c
View File

@@ -27,6 +27,8 @@
#define USB_SKEL_VENDOR_ID 0xfff0 #define USB_SKEL_VENDOR_ID 0xfff0
#define USB_SKEL_PRODUCT_ID 0xfff0 #define USB_SKEL_PRODUCT_ID 0xfff0
static DEFINE_MUTEX(skel_mutex);
/* table of devices that work with this driver */ /* table of devices that work with this driver */
static const struct usb_device_id skel_table[] = { static const struct usb_device_id skel_table[] = {
{ USB_DEVICE(USB_SKEL_VENDOR_ID, USB_SKEL_PRODUCT_ID) }, { USB_DEVICE(USB_SKEL_VENDOR_ID, USB_SKEL_PRODUCT_ID) },
@@ -100,18 +102,25 @@ static int skel_open(struct inode *inode, struct file *file)
goto exit; goto exit;
} }
mutex_lock(&skel_mutex);
dev = usb_get_intfdata(interface); dev = usb_get_intfdata(interface);
if (!dev) { if (!dev) {
mutex_unlock(&skel_mutex);
retval = -ENODEV; retval = -ENODEV;
goto exit; goto exit;
} }
/* increment our usage count for the device */ /* increment our usage count for the device */
kref_get(&dev->kref); kref_get(&dev->kref);
mutex_unlock(&skel_mutex);
/* lock the device to allow correctly handling errors /* lock the device to allow correctly handling errors
* in resumption */ * in resumption */
mutex_lock(&dev->io_mutex); mutex_lock(&dev->io_mutex);
if (!dev->interface) {
retval = -ENODEV;
goto out_err;
}
if (!dev->open_count++) { if (!dev->open_count++) {
retval = usb_autopm_get_interface(interface); retval = usb_autopm_get_interface(interface);
@@ -132,7 +141,11 @@ static int skel_open(struct inode *inode, struct file *file)
/* save our object in the file's private structure */ /* save our object in the file's private structure */
file->private_data = dev; file->private_data = dev;
out_err:
mutex_unlock(&dev->io_mutex); mutex_unlock(&dev->io_mutex);
if (retval)
kref_put(&dev->kref, skel_delete);
exit: exit:
return retval; return retval;
@@ -612,7 +625,6 @@ static void skel_disconnect(struct usb_interface *interface)
int minor = interface->minor; int minor = interface->minor;
dev = usb_get_intfdata(interface); dev = usb_get_intfdata(interface);
usb_set_intfdata(interface, NULL);
/* give back our minor */ /* give back our minor */
usb_deregister_dev(interface, &skel_class); usb_deregister_dev(interface, &skel_class);
@@ -624,8 +636,12 @@ static void skel_disconnect(struct usb_interface *interface)
usb_kill_anchored_urbs(&dev->submitted); usb_kill_anchored_urbs(&dev->submitted);
mutex_lock(&skel_mutex);
usb_set_intfdata(interface, NULL);
/* decrement our usage count */ /* decrement our usage count */
kref_put(&dev->kref, skel_delete); kref_put(&dev->kref, skel_delete);
mutex_unlock(&skel_mutex);
dev_info(&interface->dev, "USB Skeleton #%d now disconnected", minor); dev_info(&interface->dev, "USB Skeleton #%d now disconnected", minor);
} }