CVE-2024-44949

What it actually does

Insufficient cache line alignment (ARCH_DMA_MINALIGN set to 16) allows unrelated 16-byte allocations to share cache lines on PA-RISC systems, enabling DMA writes to corrupt adjacent cached data.

Why it matters to the business

On affected PA-RISC Linux systems, memory corruption can cause unpredictable application crashes, data integrity failures, or system instability, increasing operational risk and potential downtime for organizations running legacy hardware.

How an attack unfolds

An attacker with local access crafts workloads that trigger DMA operations on one allocation while another process performs cached writes to a co-located cache line, corrupting the DMA-written data and potentially leading to further exploitation via the resulting memory errors.

How to fix it

Upgrade the Linux kernel to commit 00baca74fb5879e5f9034b6156671301f500f8ee or later stable releases that set ARCH_DMA_MINALIGN to 128 on PA20 and 32 on PA1.1 and implement dynamic cache line size functions.

How to confirm the fix worked

Boot the patched kernel on PA-RISC hardware, verify cache_line_size() and dma_get_cache_alignment() return the architecture-specific values, and confirm no DMA corruption occurs under mixed DMA/cached write workloads.

Typical attack path

1. Identify PA-RISC Linux system with vulnerable kernel
2. Allocate adjacent 16-byte buffers that share a cache line
3. Trigger DMA write to one buffer while performing cached write to the other
4. Observe or leverage resulting memory corruption for further attacks

How to detect it

Review kernel boot logs and dmesg for cache line size reporting; search system logs for unexplained DMA-related errors or memory corruption events on PA-RISC systems; no specific post-exploitation artifacts are known.

What your security team should do

• Prioritize kernel upgrade on all PA-RISC systems within maintenance windows
• Audit deployed kernels for the vulnerable alignment value
• Monitor for memory corruption symptoms on affected hardware
• Plan hardware refresh or migration if PA-RISC support is deprecated