This is a note to let you know that I've just added the patch titled

staging: rtl8712: fix use-after-free in rtl8712_dl_fw

to my staging git tree which can be found at git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging.git in the staging-testing branch.

The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)

The patch will be merged to the staging-next branch sometime soon, after it passes testing, and the merge window is open.

If you have any questions about this process, please let me know.

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: 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 --- 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 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);