CVE-2021-47104

What it actually does

Incorrect goto label in error handling path of qib_user_sdma_queue_pkts() results in failure to free allocated pkt structure, causing a memory leak.

Why it matters to the business

Systems using the affected driver may experience gradual memory exhaustion, leading to degraded performance or system instability over extended periods of use.

How an attack unfolds

An attacker with ability to trigger the specific error condition in the qib_user_sdma_queue_pkts function can cause repeated allocation without corresponding frees, exhausting system memory.

How to fix it

Update to a fixed version of the Linux kernel that includes the corrected error handling for the qib driver.

How to confirm the fix worked

Review kernel source for the fix in qib_user_sdma_queue_pkts() ensuring proper cleanup label usage; test error paths to confirm no leaks.

Typical attack path

1. Identify conditions that trigger the error path in the SDMA queue packet function
2. Repeatedly invoke the affected code path to accumulate leaked memory
3. Monitor for system resource depletion

How to detect it

Monitor system logs for memory allocation warnings or OOM killer events; use memory profiling tools to detect leaks in the qib module.

What your security team should do

• Apply kernel updates promptly if using InfiniBand qib hardware
• Monitor memory usage on affected systems for unusual patterns
• Consider disabling unused drivers if applicable