CVE-2021-47032

What it actually does

Failure to unmap the first pointer in the txp structure in the mt7915 driver leaves DMA mappings active, resulting in leaked DMA mapping entries and potential exhaustion of DMA resources or subsequent memory corruption.

Why it matters to the business

Systems running affected Linux kernel wireless drivers may experience gradual resource exhaustion, instability, or crashes during sustained network transmit operations, increasing downtime and maintenance costs especially in environments with high device prevalence.

How an attack unfolds

An attacker with the ability to trigger repeated transmit operations through the mt7915 hardware path can cause incremental DMA mapping leaks; over time this may allow resource exhaustion or open paths to memory corruption that could be leveraged for denial of service or further compromise, though no public exploitation or named threat actors have been observed.

How to fix it

Update the Linux kernel or affected driver to the fixed version containing commit cd2b3e9894b26fbeebfe34a5cab5b26efab0939a; for microsoft/azure-kinect-sensor-sdk users, ensure the package is updated to the commit listed in the fixed_versions.

How to confirm the fix worked

Verify the presence of the unmap call for the first txp pointer after applying the update; review kernel logs for DMA mapping warnings and confirm no leaks under sustained transmit load using tools such as dma-debug.

Typical attack path

1. Gain local or network access sufficient to initiate transmit operations on mt7915 hardware
2. Repeatedly send crafted or high-volume frames to exercise the tx skb path
3. Accumulate unmapped DMA entries until resource limits are reached
4. Trigger system instability, crash, or attempt secondary exploitation of resulting memory state

How to detect it

Review kernel logs for DMA mapping leak indicators or mt7915 transmit errors; examine system stability trends under network load and correlate with driver version prior to the referenced commit.

What your security team should do

• Prioritize patching systems using mt7915 or dependent packages such as azure-kinect-sensor-sdk within standard maintenance windows given the 965-day publication age and low EPSS
• Monitor kernel DMA debug output and resource counters for anomalies
• Apply the exact fixed commit cd2b3e9894b26fbeebfe34a5cab5b26efab0939a where binary updates are unavailable