CVE-2026-68456: usb: atm: ueagle-atm: wait for pre-firmware load in .disconnect()
In the Linux kernel, the following vulnerability has been resolved:
usb: atm: ueagle-atm: wait for pre-firmware load in .disconnect()
ueagle-atm uses the asynchronous requestfirmwarenowait() in .probe(), but does not wait for its completion, not even in .disconnect(); so, if the device is unplugged meanwhile, its teardown runs concurrently with that.
Even though this inconsistency is worth addressing on its own, it has also triggered several bug reports in syzbot over the years (some auto-closed) where the firmware sysfs fallback mechanism (CONFIGFWLOADERUSERHELPER) creates a firmware subdirectory in the device directory during its removal, which might hit unexpected conditions in kernfs, apparently, depending at which point the add and remove operations raced. (See links.)
The pattern is:
usb ?-?: Direct firmware load for ueagle-atm/eagle?.fw failed with error -2 usb ?-?: Falling back to sysfs fallback for: ueagle-atm/eagle?.fw <ERROR> Call trace: ... kernfscreatedirns sysfscreatedirns createdir kobjectaddinternal kobjectaddvarg kobjectadd classdircreateandadd getdeviceparent deviceadd fwloadsysfsfallback fwloadfromuserhelper firmwarefallbacksysfs requestfirmware requestfirmwareworkfunc ...
(Some variations are observed, after fwloadsysfsfallback(), e.g., [1].)
While the kernfs side is being looked at, the ueagle-atm side can be fixed by waiting for the pre-firmware load in the .disconnect() handler.
This change has a similar approach to previous work by Andrey Tsygunka [2] (waitforcompletion() in .disconnect()), but it is relatively different in design/implementation; using the Originally-by tag for credit assignment.
This has been tested with: - synthetic reproducer to check the error path; - USB gadget (virtual device) to check the firmware upload path; - QEMU device emulator to check the device ID re-enumeration path; (The latter two were written by Claude; no other code/text in this commit.)
Links (year first reported): 2025 https://syzbot.org/bug?extid=ce1e5a1b4e086b43e56d 2025 https://syzbot.org/bug?extid=9af8471255ac36e34fd4 2024 https://syzbot.org/bug?extid=306212936b13e520679d 2023 https://syzkaller.appspot.com/bug?extid=457452d30bcdda75ead2 2022 https://syzbot.org/bug?extid=782984d6f1701b526edb 2021 https://syzbot.org/bug?id=f3f221579f4ef7e9691281f3c6f56c05f83e8490 2021 https://syzbot.org/bug?id=84d86f0d71394829df6fc53daf6642c045983881 2021 https://syzbot.org/bug?id=3302dc1c0e2b9c94f2e8edb404eabc9267bc6f90
[1] https://syzkaller.appspot.com/bug?extid=457452d30bcdda75ead2 [2] https://lore.kernel.org/lkml/20250410093146.3776801-2-aitsygunka@yandex.ru/
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Configuration
Control/adjust the use of the firmware sysfs fallback mechanism that relies on CONFIG_FW_LOADER_USER_HELPER (the text indicates this mechanism may hit unexpected kernfs conditions when racing).
Linux kernel CONFIG_FW_LOADER_USER_HELPER = (not explicitly set in material)
Event History
Frequently Asked Questions
What is the severity of CVE-2026-68456?
CVE-2026-68456 has a risk level of 23, indicating a potentially significant impact on security.
How do I fix CVE-2026-68456?
To fix CVE-2026-68456, ensure you update to the latest version of the Linux kernel where the vulnerability has been patched.
What systems are affected by CVE-2026-68456?
CVE-2026-68456 affects systems running the Linux kernel that utilize the ueagle-atm USB ATM driver.
What type of vulnerability is CVE-2026-68456?
CVE-2026-68456 is a resource management vulnerability caused by not properly waiting for firmware loading during device disconnection.
What are the consequences of CVE-2026-68456 if exploited?
If exploited, CVE-2026-68456 could lead to device instability or system crashes due to improper handling during disconnection.