The patch below does not apply to the 4.19-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From c052cc1a069c3e575619cf64ec427eb41176ca70 Mon Sep 17 00:00:00 2001
From: Pavel Skripkin paskripkin@gmail.com Date: Wed, 20 Oct 2021 00:17:18 +0300 Subject: [PATCH] staging: rtl8712: fix use-after-free in rtl8712_dl_fw
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") Cc: stable stable@vger.kernel.org Reported-and-tested-by: syzbot+c55162be492189fb4f51@syzkaller.appspotmail.com Signed-off-by: Pavel Skripkin paskripkin@gmail.com Link: https://lore.kernel.org/r/20211019211718.26354-1-paskripkin@gmail.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
diff --git a/drivers/staging/rtl8712/usb_intf.c b/drivers/staging/rtl8712/usb_intf.c index 17e705411e64..ee4c61f85a07 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);