CVE-2026-64455: USB: chaoskey: Fix slab-use-after-free in chaoskey_release()
In the Linux kernel, the following vulnerability has been resolved:
USB: chaoskey: Fix slab-use-after-free in chaoskeyrelease()
The chaoskey driver has a use-after-free bug in its release routine. If the user closes the device file after the USB device has been unplugged, a debugging log statement will try to access the usbinterface structure after it has been deallocated:
BUG: KASAN: slab-use-after-free in devdriverstring (drivers/base/core.c:2406) Read of size 8 at addr ffff888168e8a0b8 by task chaoskeyrawre/10106
Hardware name: QEMU Ubuntu 24.04 PC v2 (i440FX + PIIX, archcaps fix, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 Call Trace: <TASK> dumpstacklvl (lib/dumpstack.c:94 lib/dumpstack.c:120) printreport (mm/kasan/report.c:378 mm/kasan/report.c:482) kasanreport (mm/kasan/report.c:595) devdriverstring (drivers/base/core.c:2406) dynamicdevdbg (lib/dynamicdebug.c:906) chaoskeyrelease (drivers/usb/misc/chaoskey.c:323) fput (fs/filetable.c:510) fputclosesync (fs/filetable.c:615) x64sysclose (fs/open.c:1507 fs/open.c:1492 fs/open.c:1492) dosyscall64 (arch/x86/entry/syscall64.c:63 arch/x86/entry/syscall64.c:94) entrySYSCALL64afterhwframe (arch/x86/entry/entry64.S:121)
The driver's last reference to the interface structure is dropped in the chaoskeyfree() routine, so the code must not use the interface -- even in a debugging statement -- after that routine returns. (Exception: If we know that another reference is held by someone else, such as the device core while the disconnect routine runs, there's no problem. Thanks to Johan Hovold for pointing this out.)
Since the bad access is part of an unimportant debugging statement, we can fix the problem simply by removing the whole statement.
Affected Software
Remediation
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In the USB chaoskey driver's chaoskey_release() routine, remove the debugging log statement that accesses the usb_interface structure after chaoskey_free() has dropped the driver's last reference.
Event History
Frequently Asked Questions
What is the severity of CVE-2026-64455?
CVE-2026-64455 is classified with a risk score of 18, indicating a high severity level.
How do I fix CVE-2026-64455?
To mitigate CVE-2026-64455, update to the latest version of the Linux kernel where the slab-use-after-free vulnerability has been addressed.
What systems are affected by CVE-2026-64455?
CVE-2026-64455 affects systems running the vulnerable versions of the Linux kernel that include the chaoskey driver.
What impact does CVE-2026-64455 have on users?
CVE-2026-64455 could allow an attacker to exploit a use-after-free condition, potentially leading to data corruption or denial of service.
Is CVE-2026-64455 a local or remote vulnerability?
CVE-2026-64455 is considered a local vulnerability, as it requires local access to the system for exploitation.