From: Lukas Wunner <lukas@wunner.de> stable inclusion from stable-v4.19.256 commit 7f77dcbc030c2faa6d8e8a594985eeb34018409e category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/ICG9RB CVE: CVE-2022-50220 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- commit a69e617e533edddf3fa3123149900f36e0a6dc74 upstream. usbnet uses the work usbnet_deferred_kevent() to perform tasks which may sleep. On disconnect, completion of the work was originally awaited in ->ndo_stop(). But in 2003, that was moved to ->disconnect() by historic commit "[PATCH] USB: usbnet, prevent exotic rtnl deadlock": https://git.kernel.org/tglx/history/c/0f138bbfd83c The change was made because back then, the kernel's workqueue implementation did not allow waiting for a single work. One had to wait for completion of *all* work by calling flush_scheduled_work(), and that could deadlock when waiting for usbnet_deferred_kevent() with rtnl_mutex held in ->ndo_stop(). The commit solved one problem but created another: It causes a use-after-free in USB Ethernet drivers aqc111.c, asix_devices.c, ax88179_178a.c, ch9200.c and smsc75xx.c: * If the drivers receive a link change interrupt immediately before disconnect, they raise EVENT_LINK_RESET in their (non-sleepable) ->status() callback and schedule usbnet_deferred_kevent(). * usbnet_deferred_kevent() invokes the driver's ->link_reset() callback, which calls netif_carrier_{on,off}(). * That in turn schedules the work linkwatch_event(). Because usbnet_deferred_kevent() is awaited after unregister_netdev(), netif_carrier_{on,off}() may operate on an unregistered netdev and linkwatch_event() may run after free_netdev(), causing a use-after-free. In 2010, usbnet was changed to only wait for a single instance of usbnet_deferred_kevent() instead of *all* work by commit 23f333a2bfaf ("drivers/net: don't use flush_scheduled_work()"). Unfortunately the commit neglected to move the wait back to ->ndo_stop(). Rectify that omission at long last. Reported-by: Jann Horn <jannh@google.com> Link: https://lore.kernel.org/netdev/CAG48ez0MHBbENX5gCdHAUXZ7h7s20LnepBF-pa5M=7Bi... Reported-by: Oleksij Rempel <o.rempel@pengutronix.de> Link: https://lore.kernel.org/netdev/20220315113841.GA22337@pengutronix.de/ Signed-off-by: Lukas Wunner <lukas@wunner.de> Cc: stable@vger.kernel.org Acked-by: Oliver Neukum <oneukum@suse.com> Link: https://lore.kernel.org/r/d1c87ebe9fc502bffcd1576e238d685ad08321e4.165598788... Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Dong Chenchen <dongchenchen2@huawei.com> --- drivers/net/usb/usbnet.c | 8 ++------ 1 file changed, 2 insertions(+), 6 deletions(-) diff --git a/drivers/net/usb/usbnet.c b/drivers/net/usb/usbnet.c index e5c7a5c05109..1316f5b0c0d7 100644 --- a/drivers/net/usb/usbnet.c +++ b/drivers/net/usb/usbnet.c @@ -845,13 +845,11 @@ int usbnet_stop (struct net_device *net) mpn = !test_and_clear_bit(EVENT_NO_RUNTIME_PM, &dev->flags); - /* deferred work (task, timer, softirq) must also stop. - * can't flush_scheduled_work() until we drop rtnl (later), - * else workers could deadlock; so make workers a NOP. - */ + /* deferred work (timer, softirq, task) must also stop */ dev->flags = 0; del_timer_sync (&dev->delay); tasklet_kill (&dev->bh); + cancel_work_sync(&dev->kevent); if (!pm) usb_autopm_put_interface(dev->intf); @@ -1614,8 +1612,6 @@ void usbnet_disconnect (struct usb_interface *intf) net = dev->net; unregister_netdev (net); - cancel_work_sync(&dev->kevent); - usb_scuttle_anchored_urbs(&dev->deferred); if (dev->driver_info->unbind) -- 2.25.1