Syzbot reported use-after-free in rtl8712_dl_fw(). The problem was in race condition between r871xu_dev_remove() ->ndo_open() callback. It's easy to see from crash log, that driver accesses released firmware in ->ndo_open() callback. It may happen, since driver was releasing firmware _before_ unregistering netdev. Fix it by moving unregister_netdev() before cleaning up resources. Call Trace: ... rtl871x_open_fw drivers/staging/rtl8712/hal_init.c:83 [inline] rtl8712_dl_fw+0xd95/0xe10 drivers/staging/rtl8712/hal_init.c:170 rtl8712_hal_init drivers/staging/rtl8712/hal_init.c:330 [inline] rtl871x_hal_init+0xae/0x180 drivers/staging/rtl8712/hal_init.c:394 netdev_open+0xe6/0x6c0 drivers/staging/rtl8712/os_intfs.c:380 __dev_open+0x2bc/0x4d0 net/core/dev.c:1484 Freed by task 1306: ... release_firmware+0x1b/0x30 drivers/base/firmware_loader/main.c:1053 r871xu_dev_remove+0xcc/0x2c0 drivers/staging/rtl8712/usb_intf.c:599 usb_unbind_interface+0x1d8/0x8d0 drivers/usb/core/driver.c:458 Fixes: 8c213fa59199 ("staging: r8712u: Use asynchronous firmware loading") Reported-and-tested-by: syzbot+c55162be492189fb4f51@xxxxxxxxxxxxxxxxxxxxxxxxx Signed-off-by: Pavel Skripkin <paskripkin@xxxxxxxxx> --- drivers/staging/rtl8712/usb_intf.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/staging/rtl8712/usb_intf.c b/drivers/staging/rtl8712/usb_intf.c index 505ebeb643dc..cae04272deff 100644 --- a/drivers/staging/rtl8712/usb_intf.c +++ b/drivers/staging/rtl8712/usb_intf.c @@ -595,12 +595,12 @@ static void r871xu_dev_remove(struct usb_interface *pusb_intf) /* never exit with a firmware callback pending */ wait_for_completion(&padapter->rtl8712_fw_ready); + if (pnetdev->reg_state != NETREG_UNINITIALIZED) + unregister_netdev(pnetdev); /* will call netdev_close() */ usb_set_intfdata(pusb_intf, NULL); release_firmware(padapter->fw); if (drvpriv.drv_registered) padapter->surprise_removed = true; - if (pnetdev->reg_state != NETREG_UNINITIALIZED) - unregister_netdev(pnetdev); /* will call netdev_close() */ r8712_flush_rwctrl_works(padapter); r8712_flush_led_works(padapter); udelay(1); -- 2.33.1