CVE-2026-68363

In the Linux kernel, the following vulnerability has been resolved:

wifi: ath9k: hif_usb: don't dereference hif_dev after re-arming firmware request

ath9k_hif_request_firmware() re-arms an asynchronous firmware load via

request_firmware_nowait(), passing hif_dev as the completion context, and

then still dereferences hif_dev:

dev_info(&hif_dev->udev->dev, "ath9k_htc: Firmware %s requested\n",

hif_dev->fw_name);

The re-armed callback ath9k_hif_usb_firmware_cb() runs on the "events"

workqueue and, when the firmware is missing, walks the retry chain into

ath9k_hif_usb_firmware_fail() -> complete_all(&hif_dev->fw_done). That

releases the wait_for_completion(&hif_dev->fw_done) in a concurrent

ath9k_hif_usb_disconnect(), which then kfree()s hif_dev. The trailing

dev_info() in the frame that re-armed the request can therefore read freed

memory (hif_dev->udev, the first field of struct hif_device_usb):

BUG: KASAN: slab-use-after-free in ath9k_hif_request_firmware

Read of size 8 ... by task kworker/...

ath9k_hif_request_firmware

ath9k_hif_usb_firmware_cb drivers/net/wireless/ath/ath9k/hif_usb.c:1247

request_firmware_work_func

Allocated by ...:

ath9k_hif_usb_probe drivers/net/wireless/ath/ath9k/hif_usb.c

Freed by ...:

ath9k_hif_usb_disconnect -> kfree drivers/net/wireless/ath/ath9k/hif_usb.c

The fw_done barrier only makes disconnect wait for the firmware chain to

*terminate*; it does not protect the outer ath9k_hif_request_firmware()

frame that re-armed the request and keeps touching hif_dev afterwards.

Drop the post-request dev_info(): it is the only use of hif_dev after the

async request is armed, and it is purely informational (the dev_err() on the

failure path runs only when request_firmware_nowait() did not arm a callback,

so hif_dev is still alive there).

This was first reported by syzbot as a single, non-reproduced crash that was

later auto-obsoleted, and was independently rediscovered by the reFuzz fuzzer,

which produced a C reproducer (USB-gadget connect/disconnect of an ath9k_htc

device whose firmware download fails). The vulnerable code is unchanged and

still present in v7.1-rc6, where the slab-use-after-free reproduces under KASAN

once the (sub-microsecond) race window is widened.