CVE-2021-47401

What it actually does

The ipoctal tty driver allocated its device name on the kernel stack and continued using the pointer after driver registration, allowing user-space reads to expose adjacent stack memory contents.

Why it matters to the business

Attackers with local access can obtain fragments of kernel memory that may contain credentials, pointers, or other sensitive data, increasing the risk of privilege escalation or further compromise on Linux systems using the affected staging driver.

How an attack unfolds

An attacker loads or ensures the ipoctal module is present, opens the resulting tty device node, and reads from it to retrieve the leaked stack contents that were left behind by the improperly scoped driver name buffer.

How to fix it

Upgrade to a Linux kernel version containing the fix for the ipoctal stack allocation; remove or blacklist the ipoctal module if the functionality is unused.

How to confirm the fix worked

Confirm the driver source no longer declares the tty name buffer on the stack and that the device registers without leaking adjacent memory; test by opening the tty node and verifying no unexpected stack data is readable.

Typical attack path

1. Identify a system exposing the ipoctal tty device node
2. Open the device with standard user privileges
3. Perform read operations that trigger the post-registration name usage
4. Extract and parse leaked stack bytes for useful kernel data

How to detect it

Review kernel logs for ipoctal registration messages, inspect process activity opening /dev/ttyIPO* nodes, and look for unexpected user-space reads from those devices shortly after module load.

What your security team should do

• Apply the upstream kernel patch or vendor update that moves the tty name off the stack
• Audit systems for presence of the ipoctal staging driver and disable it where possible
• Monitor for local users opening unexpected tty devices from this driver