CVE-2026-99028: Linux Vulnerability

Description

In the Linux kernel, the following vulnerability has been resolved: net: xilinx: axienet: Free outstanding DMA buffers on dmaengine stop In the dmaengine path the driver pre-submits RX buffers and holds in-flight TX buffers whose SKBs are DMA-mapped by the driver and freed only in the completion callbacks. On ndo_stop() dmaengine_terminate_sync() aborts these descriptors without running their callbacks, and the driver then frees only the ring shells, leaking every SKB still owned by the engine and its DMA mapping on each ifdown. With 128 RX buffers pre-posted per channel, the mapping leak can eventually exhaust a limited IOMMU aperture. Clear the slot's skb in the TX and RX callbacks so a non-NULL skb marks a slot that still owns a live, DMA-mapped buffer, and on stop unmap and free every such buffer. axienet_dma_rx_cb() runs from the DMA tasklet and re-arms the RX ring on each completion, so it can race axienet_stop(): a completion may submit a fresh buffer after dmaengine_terminate_sync() has returned, leaving the channel armed with a buffer the teardown then frees while the engine may still write into it (dma_release_channel() does not stop it either). Add a lock that axienet_dma_rx_cb() holds across the @stopping check and the resubmit, and axienet_stop() holds to set @stopping before terminating. Once @stopping is set no callback can arm a new buffer, and any armed just before is aborted by the terminate, so teardown only frees buffers the engine no longer owns.

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

Vendor	Product	Versions
Linux	Linux	>= 6a91b846af85a24241decd686269e8e038eb13d1, < 079396129da5e7cb40ca0920aa1b9525bef6097c; >= 6a91b846af85a24241decd686269e8e038eb13d1, < eececf7c3a679d9c08175ad6bacbc8c31848f5af; >= 6a91b846af85a24241decd686269e8e038eb13d1, < 5e5cf3ad7c099ff86ea9e422cddb25a2e5317b58; >= 6a91b846af85a24241decd686269e8e038eb13d1, < bcf2573a68a808a5b54cadafa72b6672e662c2bf
Linux	Linux	6.8

References

Timeline

Published: Oct 23, 2026
Last Modified: Oct 23, 2026
Status: Received

Frequently Asked Questions

What is CVE-2026-99028?

In the Linux kernel, the following vulnerability has been resolved: net: xilinx: axienet: Free outstanding DMA buffers on dmaengine stop In the dmaengine path the driver pre-submits RX buffers and holds in-flight TX buffers whose SKBs are DMA-mapped by the driver and freed only in the completion callbacks. On ndo_stop() dmaengine_terminate_sync() aborts these descriptors without running their callbacks, and the driver then frees only the ring shells, leaking every SKB still owned by the engine and its DMA mapping on each ifdown. With 128 RX buffers pre-posted per channel, the mapping leak can eventually exhaust a limited IOMMU aperture. Clear the slot's skb in the TX and RX callbacks so a non-NULL skb marks a slot that still owns a live, DMA-mapped buffer, and on stop unmap and free every such buffer. axienet_dma_rx_cb() runs from the DMA tasklet and re-arms the RX ring on each completion, so it can race axienet_stop(): a completion may submit a fresh buffer after dmaengine_terminate_sync() has returned, leaving the channel armed with a buffer the teardown then frees while the engine may still write into it (dma_release_channel() does not stop it either). Add a lock that axienet_dma_rx_cb() holds across the @stopping check and the resubmit, and axienet_stop() holds to set @stopping before terminating. Once @stopping is set no callback can arm a new buffer, and any armed just before is aborted by the terminate, so teardown only frees buffers the engine no longer owns.

How severe is CVE-2026-99028?

Severity scoring for CVE-2026-99028 is pending analysis.

How do I fix CVE-2026-99028?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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