From: Cheng Yongkang Date: Fri, 5 Jun 2026 15:32:10 +0000 (-0700) Subject: wifi: ath9k: hif_usb: don't dereference hif_dev after re-arming firmware request X-Git-Url: http://git.ipfire.org/gitweb/index.cgi?a=commitdiff_plain;h=dad9f96945d77ecd4708f730c06ef54dcd8cc057;p=thirdparty%2Fkernel%2Flinux.git 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. Fixes: e904cf6fe230 ("ath9k_htc: introduce support for different fw versions") Reported-by: syzbot+50122cbc2874b1eb25b0@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=50122cbc2874b1eb25b0 Signed-off-by: Cheng Yongkang Acked-by: Toke Høiland-Jørgensen Link: https://patch.msgid.link/20260605153210.20471-1-1020691186@qq.com Signed-off-by: Jeff Johnson --- diff --git a/drivers/net/wireless/ath/ath9k/hif_usb.c b/drivers/net/wireless/ath/ath9k/hif_usb.c index 515267f48d80..47f904e7e652 100644 --- a/drivers/net/wireless/ath/ath9k/hif_usb.c +++ b/drivers/net/wireless/ath/ath9k/hif_usb.c @@ -1215,15 +1215,10 @@ static int ath9k_hif_request_firmware(struct hif_device_usb *hif_dev, ret = request_firmware_nowait(THIS_MODULE, true, hif_dev->fw_name, &hif_dev->udev->dev, GFP_KERNEL, hif_dev, ath9k_hif_usb_firmware_cb); - if (ret) { + if (ret) dev_err(&hif_dev->udev->dev, "ath9k_htc: Async request for firmware %s failed\n", hif_dev->fw_name); - return ret; - } - - dev_info(&hif_dev->udev->dev, "ath9k_htc: Firmware %s requested\n", - hif_dev->fw_name); return ret; }