From ab4a0b8fcb9a95c02909b62049811bd2e586aaa4 Mon Sep 17 00:00:00 2001 From: Pavel Skripkin Date: Thu, 17 Jun 2021 21:51:30 +0300 Subject: net: can: ems_usb: fix use-after-free in ems_usb_disconnect() In ems_usb_disconnect() dev pointer, which is netdev private data, is used after free_candev() call: | if (dev) { | unregister_netdev(dev->netdev); | free_candev(dev->netdev); | | unlink_all_urbs(dev); | | usb_free_urb(dev->intr_urb); | | kfree(dev->intr_in_buffer); | kfree(dev->tx_msg_buffer); | } Fix it by simply moving free_candev() at the end of the block. Fail log: | BUG: KASAN: use-after-free in ems_usb_disconnect | Read of size 8 at addr ffff88804e041008 by task kworker/1:2/2895 | | CPU: 1 PID: 2895 Comm: kworker/1:2 Not tainted 5.13.0-rc5+ #164 | Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a-rebuilt.opensuse.4 | Workqueue: usb_hub_wq hub_event | Call Trace: | dump_stack (lib/dump_stack.c:122) | print_address_description.constprop.0.cold (mm/kasan/report.c:234) | kasan_report.cold (mm/kasan/report.c:420 mm/kasan/report.c:436) | ems_usb_disconnect (drivers/net/can/usb/ems_usb.c:683 drivers/net/can/usb/ems_usb.c:1058) Fixes: 702171adeed3 ("ems_usb: Added support for EMS CPC-USB/ARM7 CAN/USB interface") Link: https://lore.kernel.org/r/20210617185130.5834-1-paskripkin@gmail.com Cc: linux-stable Signed-off-by: Pavel Skripkin Signed-off-by: Marc Kleine-Budde --- drivers/net/can/usb/ems_usb.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/net/can/usb/ems_usb.c b/drivers/net/can/usb/ems_usb.c index 5af69787d9d5..0a37af4a3fa4 100644 --- a/drivers/net/can/usb/ems_usb.c +++ b/drivers/net/can/usb/ems_usb.c @@ -1053,7 +1053,6 @@ static void ems_usb_disconnect(struct usb_interface *intf) if (dev) { unregister_netdev(dev->netdev); - free_candev(dev->netdev); unlink_all_urbs(dev); @@ -1061,6 +1060,8 @@ static void ems_usb_disconnect(struct usb_interface *intf) kfree(dev->intr_in_buffer); kfree(dev->tx_msg_buffer); + + free_candev(dev->netdev); } } -- cgit v1.2.3-59-g8ed1b