CVE-2021-47083

What it actually does

Out-of-bounds array access in the MediaTek pinctrl driver when a virtual EINT number exceeds the GPIO count, leading to global buffer overflow in desc[eint_n].

Why it matters to the business

May cause kernel instability or crashes on systems using affected MediaTek hardware; low likelihood of exploitation given age and minimal observed activity reduces operational risk.

How an attack unfolds

An attacker with local access crafts input or hardware configuration that sets an EINT number larger than the GPIO limit, triggering the driver to index beyond the allocated descriptor array and potentially corrupt kernel memory.

How to fix it

Update to a Linux kernel containing the fix for this out-of-bounds issue in the pinctrl-mediatek driver; apply vendor or distribution backports as available.

How to confirm the fix worked

Confirm kernel version includes the pinctrl mediatek bounds check commit; review driver source for the eint_n versus gpio_nr comparison before array access.

Typical attack path

1. Obtain local code execution or shell on target system
2. Trigger pinctrl-mediatek EINT registration or interrupt setup with oversized virtual number
3. Cause out-of-bounds read/write into global descriptor array
4. Escalate to kernel code execution or denial of service

How to detect it

Review kernel logs for pinctrl-mediatek warnings or oops involving EINT or descriptor array indexing; examine crash dumps for out-of-bounds accesses in the driver.

What your security team should do

• Prioritize kernel updates on MediaTek-based embedded or Android devices
• Monitor EPSS and KEV status for any future increase in activity
• Restrict unprivileged local access where feasible until patched