CVE-2023-53475

What it actually does

The flaw allows a sleeping function (kasprintf via tegra_xusb_find_port) to be invoked from atomic context in the tegra_xusb_usb_phy_work workqueue path when handling dual-role USB port mode switches on Tegra XHCI controllers.

Why it matters to the business

Systems using affected Tegra-based hardware may experience unexpected kernel crashes or instability during USB host mode transitions, leading to downtime and potential data loss in embedded or server deployments; the issue has low exploitability and no known ransomware use despite being public for over a year.

How an attack unfolds

An attacker or legitimate workload triggers a USB dual-role port switch to host mode, causing the atomic_notifier_call_chain to invoke tegra_xhci_id_notify which calls into tegra_xusb_padctl_get_usb3_companion and ultimately kasprintf from within the events workqueue, violating atomic context rules and triggering a BUG.

How to fix it

Update the Linux kernel to a version containing commit b4b4f17aa46c025da77aed5133b08971959c9684 or later; rebuild and deploy the fixed kernel image on affected Tegra platforms, then reboot.

How to confirm the fix worked

Confirm the running kernel contains commit b4b4f17aa46c025da77aed5133b08971959c9684 via git log or uname; reproduce a dual-role port switch and verify absence of the sleeping-function BUG splat in dmesg.

Typical attack path

1. Trigger dual-role USB port mode change to host on affected Tegra hardware
2. Workqueue tegra_xusb_usb_phy_work executes tegra_xhci_id_notify
3. atomic_notifier_call_chain leads to tegra_xusb_padctl_get_usb3_companion
4. tegra_xusb_find_port calls kasprintf which attempts to sleep
5. Kernel BUG halts execution due to sleeping in atomic context

How to detect it

Search kernel logs for the exact BUG splat mentioning sleeping function called from invalid context at include/linux/sched/mm.h combined with tegra_xusb_usb_phy_work and kasprintf; review workqueue and notifier call traces on systems with Tegra XHCI controllers.

What your security team should do

• Prioritize kernel upgrades on all Tegra XHCI systems within standard patch windows given low EPSS and no KEV listing
• Monitor for similar atomic/sleep issues in USB and workqueue code during future kernel updates
• Test USB dual-role functionality post-upgrade in staging environments before broad rollout