# CVE-2026-68363: wifi: ath9k: hif_usb: don't dereference hif_dev after re-arming firmware request

Status: published. Published: 2026-08-10. Updated: 2026-11-06.

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.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- Linux / Linux: ≥ e904cf6fe23022cde4e0ea9d41601411a315a3dc; < 47ed81aaa7f94d9808f4719e78a760c2ec1e6c86 (affected, git); ≥ e904cf6fe23022cde4e0ea9d41601411a315a3dc; < 48de0c6952192b0771fca468df4364d11ec74ad9 (affected, git); ≥ e904cf6fe23022cde4e0ea9d41601411a315a3dc; < 063497cc9f320ab71a7a937c3bc0a23e630aefe2 (affected, git); ≥ e904cf6fe23022cde4e0ea9d41601411a315a3dc; < 7f184ca38a90889f3f6665ff96748b95da39dbee (affected, git); ≥ e904cf6fe23022cde4e0ea9d41601411a315a3dc; < 10b0ce629123a3737b4eda50188f73bb7be7b68b (affected, git); ≥ e904cf6fe23022cde4e0ea9d41601411a315a3dc; < 48a69cedde7388294e4ea6fd804156cd62bc04fc (affected, git); ≥ e904cf6fe23022cde4e0ea9d41601411a315a3dc; < 7c9046d92c4b9789c9d9d775e4fd5f34be64cb0a (affected, git); ≥ e904cf6fe23022cde4e0ea9d41601411a315a3dc; < dad9f96945d77ecd4708f730c06ef54dcd8cc057 (affected, git). Source: CNA: Linux
- Linux / Linux: 4.4 (affected); ≥ 0; < 4.4 (unaffected, semver); ≥ 5.10.265; ≤ 5.10.* (unaffected, semver); ≥ 5.15.216; ≤ 5.15.* (unaffected, semver); ≥ 6.1.183; ≤ 6.1.* (unaffected, semver); ≥ 6.6.148; ≤ 6.6.* (unaffected, semver); ≥ 6.12.101; ≤ 6.12.* (unaffected, semver); ≥ 6.18.42; ≤ 6.18.* (unaffected, semver); ≥ 7.1.6; ≤ 7.1.* (unaffected, semver); ≥ 7.2; ≤ * (unaffected, original_commit_for_fix). Source: CNA: Linux

## Severity and prioritization

- CISA KEV: No listing in collected sources

- EPSS: 0.18% as of 2026-11-06; percentile 8.11%

- SSVC: exploitation none; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: Not reported

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://git.kernel.org/stable/c/47ed81aaa7f94d9808f4719e78a760c2ec1e6c86 (CNA: Linux)

- https://git.kernel.org/stable/c/48de0c6952192b0771fca468df4364d11ec74ad9 (CNA: Linux)

- https://git.kernel.org/stable/c/063497cc9f320ab71a7a937c3bc0a23e630aefe2 (CNA: Linux)

- https://git.kernel.org/stable/c/7f184ca38a90889f3f6665ff96748b95da39dbee (CNA: Linux)

- https://git.kernel.org/stable/c/10b0ce629123a3737b4eda50188f73bb7be7b68b (CNA: Linux)

- https://git.kernel.org/stable/c/48a69cedde7388294e4ea6fd804156cd62bc04fc (CNA: Linux)

- https://git.kernel.org/stable/c/7c9046d92c4b9789c9d9d775e4fd5f34be64cb0a (CNA: Linux)

- https://git.kernel.org/stable/c/dad9f96945d77ecd4708f730c06ef54dcd8cc057 (CNA: Linux)

- https://git.kernel.org/stable/c/063497cc9f320ab71a7a937c3bc0a23e630aefe2 (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

- https://git.kernel.org/stable/c/10b0ce629123a3737b4eda50188f73bb7be7b68b (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

- https://git.kernel.org/stable/c/47ed81aaa7f94d9808f4719e78a760c2ec1e6c86 (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

- https://git.kernel.org/stable/c/48a69cedde7388294e4ea6fd804156cd62bc04fc (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

- https://git.kernel.org/stable/c/48de0c6952192b0771fca468df4364d11ec74ad9 (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

- https://git.kernel.org/stable/c/7c9046d92c4b9789c9d9d775e4fd5f34be64cb0a (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

- https://git.kernel.org/stable/c/7f184ca38a90889f3f6665ff96748b95da39dbee (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

- https://git.kernel.org/stable/c/dad9f96945d77ecd4708f730c06ef54dcd8cc057 (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

## Provenance

- CNA: Linux: https://www.cve.org/CVERecord?id=CVE-2026-68363; retrieved 2026-11-06; source updated 2026-11-06

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-68363; retrieved 2026-11-06; source updated 2026-11-06

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-68363; retrieved 2026-11-06; source updated Not reported

Revision: f11c647ee652a8d91d525d3c0f29650348f24627c2ad411b78e4f73d22f4b31b

Canonical: https://y2.dev/cve/CVE-2026-68363

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