CVE-2021-47206

What it actually does

Unchecked return value from platform_get_resource() allows a NULL pointer to be dereferenced in the ohci-tmio USB host controller driver, resulting in a kernel null-pointer dereference.

Why it matters to the business

Systems using the affected TMIO USB hardware may experience kernel crashes or denial-of-service conditions when the resource lookup fails, disrupting USB functionality and requiring reboots.

How an attack unfolds

An attacker with local access or the ability to influence device initialization triggers the ohci-tmio probe path where platform_get_resource returns NULL; the missing NULL check then causes an immediate kernel panic via dereference of the invalid pointer.

How to fix it

Update the Linux kernel to a version containing the fix for the null-pointer dereference in ohci-tmio; apply the upstream commit that adds the missing return-value check after platform_get_resource.

How to confirm the fix worked

Inspect kernel source for the presence of the return-value check after platform_get_resource in drivers/usb/host/ohci-tmio.c; confirm the running kernel version includes the patch or verify via kernel log that the driver initializes without the prior NULL dereference path.

Typical attack path

1. Gain local execution or control over device tree / platform data presented to the kernel
2. Trigger loading or probing of the ohci-tmio driver
3. Cause platform_get_resource to return NULL (e.g., malformed platform data)
4. Execute the unchecked dereference leading to kernel oops/panic

How to detect it

Review kernel logs (dmesg, /var/log/kern.log, journalctl) for oops or panic messages containing ohci-tmio and platform_get_resource; look for null pointer dereference stack traces during USB host initialization.

• ohci-tmio.*platform_get_resource
• NULL pointer dereference.*ohci_tmio
• kernel: BUG: unable to handle kernel NULL pointer dereference.*ohci

What your security team should do

• Identify systems exposing the ohci-tmio driver and schedule kernel updates
• Monitor for kernel oops reports referencing ohci-tmio or platform_get_resource
• Apply the fix as a priority on any embedded or legacy hardware still using this controller