CVE-2023-54266

What it actually does

The flaw is a memory leak in m920x_i2c_xfer() where the 'read' buffer allocated for I2C transfers is freed only on the NULL path but remains allocated when m920x_read() fails, allowing repeated small allocations without corresponding frees.

Why it matters to the business

Systems using DVB-USB m920x devices may experience gradual kernel memory exhaustion over time, leading to reduced stability or the need for reboots in long-running media or broadcast environments.

How an attack unfolds

An attacker with local access or control over a connected m920x USB device can induce repeated read errors during I2C transfers to trigger the leak path, slowly consuming kernel memory until denial of service occurs.

How to fix it

Upgrade the Linux kernel to a fixed version such as 4.14.326 or apply commit 809623fedc31f4e74039d93bb75a8993635d7534 (or later) in the stable tree.

How to confirm the fix worked

Verify the running kernel contains the fix commit or is at version 4.14.326 or newer; inspect m920x_i2c_xfer() source to confirm the error path now properly frees the buffer.

Typical attack path

1. Attach or emulate an m920x USB device
2. Trigger repeated I2C xfer operations that cause m920x_read() failures
3. Accumulate unfreed buffers until memory pressure impacts the system

How to detect it

Review kernel logs and memory accounting for repeated small allocations without frees originating from the m920x driver; correlate with device attach events or I2C error patterns in dmesg.

What your security team should do

• Patch affected kernels to the listed fixed versions as soon as practical
• Monitor memory usage on systems with m920x devices until patched
• Disable or replace unsupported DVB-USB hardware if upgrades are not feasible