CVE-2024-50297

What it actually does

Race condition in Xilinx AXI Ethernet driver where Tx packets are enqueued in DQL after DMA engine start, allowing dql_completed to dequeue before enqueue and triggering kernel BUG at lib/dynamic_queue_limits.c:99 during completion callbacks.

Why it matters to the business

Kernel crashes during high-volume network workloads reduce system availability and stability for affected Linux devices; low EPSS and absence from KEV indicate limited real-world risk despite 692 days since publication.

How an attack unfolds

An attacker or automated stress tool (e.g., iperf) floods Tx traffic on an axienet interface; DMA engine starts before DQL enqueue, causing premature dequeue in axienet_dma_tx_cb and xilinx_dma_do_tasklet, resulting in BUG. No confirmed exploitation by listed threat actors or ransomware campaigns.

How to fix it

Apply the kernel fix that moves DQL enqueue before DMA engine start; upgrade flashplugin-nonfree (Ubuntu:14.04:LTS) to 11.2.202.554ubuntu0.14.04.1 or later where listed as fixed.

How to confirm the fix worked

Confirm driver source shows DQL enqueue preceding dmaengine start; reproduce iperf stress test without triggering dql_completed BUG; verify no Oops in dmesg referencing axienet_dma_tx_cb.

Typical attack path

1. Send high-rate Tx packets or run network stress test on axienet interface
2. DMA engine begins transfer before DQL enqueue completes
3. Completion tasklet calls dql_completed on unqueued entry
4. Kernel BUG at dynamic_queue_limits.c:99 triggers panic

How to detect it

Search kernel logs and dmesg for 'kernel BUG at lib/dynamic_queue_limits.c:99', 'dql_completed+0x238', 'axienet_dma_tx_cb', and tasklet crashes during high Tx load; correlate with axienet interfaces under iperf-like traffic.

• kernel BUG at lib/dynamic_queue_limits.c:99
• dql_completed+0x238/0x248
• axienet_dma_tx_cb+0xa0/0x170
• xilinx_dma_do_tasklet

What your security team should do

• Patch affected kernels with the DQL ordering fix at earliest maintenance window
• Monitor kernel logs for dql_completed BUG signatures on systems using axienet
• Limit unnecessary network stress workloads until patched
• Track EPSS trend (stable at ~0.0028) for any future increase