On Tue, Sep 22, 2020 at 03:25:25PM +0800, Jing Xiangfeng wrote: > rio_mport_add_riodev() misses to call put_device() when the device > already exists. Add the missed function call to fix it. >
Looks good. Reviewed-by: Dan Carpenter <[email protected]> I notice that rio_mport_del_riodev() has a related bug. 1802 err = rio_add_device(rdev); 1803 if (err) 1804 goto cleanup; 1805 rio_dev_get(rdev); ^^^^^^^^^^^^^^^^^ This calls get_device(&rdev->dev); 1806 1807 return 0; 1808 cleanup: 1809 kfree(rdev); 1810 return err; 1811 } 1812 1813 static int rio_mport_del_riodev(struct mport_cdev_priv *priv, void __user *arg) 1814 { 1815 struct rio_rdev_info dev_info; 1816 struct rio_dev *rdev = NULL; 1817 struct device *dev; 1818 struct rio_mport *mport; 1819 struct rio_net *net; 1820 1821 if (copy_from_user(&dev_info, arg, sizeof(dev_info))) 1822 return -EFAULT; 1823 dev_info.name[sizeof(dev_info.name) - 1] = '\0'; 1824 1825 mport = priv->md->mport; 1826 1827 /* If device name is specified, removal by name has priority */ 1828 if (strlen(dev_info.name)) { 1829 dev = bus_find_device_by_name(&rio_bus_type, NULL, 1830 dev_info.name); 1831 if (dev) 1832 rdev = to_rio_dev(dev); This path takes a second get_device(&rdev->dev); 1833 } else { 1834 do { 1835 rdev = rio_get_comptag(dev_info.comptag, rdev); 1836 if (rdev && rdev->dev.parent == &mport->net->dev && 1837 rdev->destid == dev_info.destid && 1838 rdev->hopcount == dev_info.hopcount) 1839 break; This path does not call get_device(). 1840 } while (rdev); 1841 } 1842 1843 if (!rdev) { 1844 rmcd_debug(RDEV, 1845 "device name:%s ct:0x%x did:0x%x hc:0x%x not found", 1846 dev_info.name, dev_info.comptag, dev_info.destid, 1847 dev_info.hopcount); 1848 return -ENODEV; 1849 } 1850 1851 net = rdev->net; 1852 rio_dev_put(rdev); This drops a reference. 1853 rio_del_device(rdev, RIO_DEVICE_SHUTDOWN); This drops a second reference. So presumably deleting by component tag will lead to a use after free. 1854 1855 if (list_empty(&net->devices)) { 1856 rio_free_net(net); 1857 mport->net = NULL; 1858 } 1859 1860 return 0; 1861 } regards, dan carpenter
