Description
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.
Published: 2026-08-10
Score: n/a
EPSS: n/a
KEV: No
Impact: n/a
Action: n/a
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History

Mon, 10 Aug 2026 12:30:00 +0000

Type Values Removed Values Added
Description 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.
Title wifi: ath9k: hif_usb: don't dereference hif_dev after re-arming firmware request
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
References

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Linux Linux Kernel
cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2026-08-10T12:03:40.355Z

Reserved: 2026-07-30T09:28:09.385Z

Link: CVE-2026-68363

cve-icon Vulnrichment

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cve-icon NVD

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