From: Alan Stern Date: Tue, 24 Jun 2008 18:47:19 +0000 (-0400) Subject: usbfs: fix race between open and unregister X-Git-Tag: v2.6.27-rc1~946^2~14 X-Git-Url: http://pilppa.com/gitweb/?a=commitdiff_plain;h=d64aac36394b3c26db53538bfedd8444a3a2206e;p=linux-2.6-omap-h63xx.git usbfs: fix race between open and unregister This patch (as1106) fixes a race between opening and unregistering device files in usbfs. The current code drops its reference to the device and then reacquires it, ignoring the possibility that the device structure might have been removed in the meantime. It also doesn't check whether the device is already in the NOTATTACHED state when the file is opened. Signed-off-by: Alan Stern Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c index 57bedcebf96..c44e98f6099 100644 --- a/drivers/usb/core/devio.c +++ b/drivers/usb/core/devio.c @@ -562,7 +562,6 @@ static struct usb_device *usbdev_lookup_by_devt(dev_t devt) dev = bus_find_device(&usb_bus_type, NULL, (void *) devt, match_devt); if (!dev) return NULL; - put_device(dev); return container_of(dev, struct usb_device, dev); } @@ -591,16 +590,21 @@ static int usbdev_open(struct inode *inode, struct file *file) dev = usbdev_lookup_by_devt(inode->i_rdev); #ifdef CONFIG_USB_DEVICEFS /* procfs file */ - if (!dev) + if (!dev) { dev = inode->i_private; + if (dev && dev->usbfs_dentry && + dev->usbfs_dentry->d_inode == inode) + usb_get_dev(dev); + else + dev = NULL; + } #endif - if (!dev) + if (!dev || dev->state == USB_STATE_NOTATTACHED) goto out; ret = usb_autoresume_device(dev); if (ret) goto out; - usb_get_dev(dev); ret = 0; ps->dev = dev; ps->file = file; @@ -620,8 +624,10 @@ static int usbdev_open(struct inode *inode, struct file *file) list_add_tail(&ps->list, &dev->filelist); file->private_data = ps; out: - if (ret) + if (ret) { kfree(ps); + usb_put_dev(dev); + } mutex_unlock(&usbfs_mutex); unlock_kernel(); return ret;