CVE-2021-47158

What it actually does

Missing error paths in sja1105_setup allow sja1105_static_config_load, sja1105_clocking_setup or sja1105_devlink_setup failures to return without releasing allocated resources, producing a kernel memory leak.

Why it matters to the business

Repeated driver initialization failures can gradually exhaust kernel memory, leading to reduced system stability or eventual denial of service on affected network hardware.

How an attack unfolds

An attacker with the ability to trigger repeated failures of the sja1105 DSA driver setup routines (for example via crafted device-tree or hardware faults) can cause unbounded memory allocations that are never freed.

How to fix it

Apply the upstream commit that adds the missing cleanup path; update to a Linux kernel containing the fix for CVE-2021-47158.

How to confirm the fix worked

Inspect the sja1105_setup function in the running kernel source or binary for the presence of the error-handling and cleanup label; confirm driver initialization no longer leaks on injected failures.

Typical attack path

1. Gain ability to induce sja1105 driver probe or setup errors
2. Force repeated calls to sja1105_setup that hit a failing sub-function
3. Accumulate leaked kernel memory until system resources are exhausted

How to detect it

Review kernel logs for repeated sja1105 initialization failures; track kmemleak reports or slabinfo growth associated with sja1105 allocations; correlate with hardware reset or probe events.

What your security team should do

• Prioritize kernel updates on systems using NXP SJA1105 switches
• Monitor kernel memory usage and slab statistics for unexpected growth tied to the DSA driver
• Test driver reload and error paths in staging environments before production deployment