CVE-2023-54083

What it actually does

Use-after-free in the Tegra xUSB PHY driver occurs when the dual-role port device is destroyed without clearing the usb_phy dev's driver reference, leaving a dangling pointer that KASAN can detect on subsequent access.

Why it matters to the business

Kernel memory corruption risk on systems using the affected Tegra USB PHY code can lead to crashes, instability, or potential privilege escalation during USB port teardown or hotplug events, increasing operational downtime and patching urgency for affected Linux distributions and embedded devices.

How an attack unfolds

An attacker with local access triggers repeated creation and destruction of a dual-role USB port device while the usb_phy structure still holds a reference to the now-freed driver; this dangling reference is later dereferenced, resulting in a use-after-free that may be leveraged for memory corruption or code execution.

How to fix it

Update the Linux kernel to a version containing commit b6a107c52073496d2e5d2837915f59fb3103832f (or equivalent 0eb493e3837a35cb701c1aa7e9166d3d33a19f41) which clears the driver reference from the usb_phy dev before destruction.

How to confirm the fix worked

Confirm the patch is applied by checking for the presence of the reference-clearing code in phy/tegra/xusb.c or by verifying the kernel commit hash; test by exercising dual-role port attach/detach sequences under KASAN to ensure no use-after-free reports occur.

Typical attack path

1. Obtain local access on a system with the vulnerable Tegra xUSB PHY driver enabled
2. Trigger dual-role port device creation and assignment of the port dev driver to usb_phy
3. Destroy the port device without clearing the usb_phy reference
4. Force subsequent access to the stale driver pointer through USB operations or module unload
5. Exploit the resulting use-after-free for memory corruption or escalation

How to detect it

Review kernel logs for KASAN use-after-free reports mentioning usb_phy or tegra xusb during USB port destruction; examine dmesg and audit logs around USB hotplug or module unload events for suspicious crashes or warnings.

What your security team should do

• Prioritize kernel upgrades on all Tegra-based systems within standard change windows
• Enable KASAN or similar memory debugging in test environments to validate the fix
• Monitor for USB-related oops or crashes as indirect indicators until patched