CVE-2026-80934: Linux Vulnerability

Description

In the Linux kernel, the following vulnerability has been resolved: wifi: mt76: mt7996: fix TX DMA mapping leak for AddBA req frames mt7996/mt7992 hand the firmware a HW MAC-TXP for AddBA req action frames (MT_TXD7_MAC_TXD, set in mt7996_mac_write_txwi_80211()), but are otherwise FW-TXP devices. On tx free mt76_connac_txp_skb_unmap() therefore decodes the per-frame txp as a struct mt76_connac_fw_txp. For a MAC-TXP the fw_txp.nbuf byte aliases the AddBA TID word (MT_TXP1_TID_ADDBA), which is always zero, so the unmap loop runs zero times and the skb DMA mapping in buf[1] is never unmapped. buf[1].skip_unmap is set unconditionally, so the generic DMA-ring cleanup skips it as well. Each AddBA req therefore leaks one TX DMA mapping, roughly one per (re)association. With WED enabled these mappings are bounced through the WED swiotlb pool, so under continuous client reconnect churn the pool is exhausted after ~1-2 days, after which DMA mapping fails for WED, the WiFi MCU and other on-SoC consumers. Keep the deferred (token release) unmap that the design relies on, and add an mt7996-specific txp unmap that inspects MT_TXD7_MAC_TXD and unmaps buf[1] from the MAC-TXP layout for those frames, delegating to mt76_connac_txp_skb_unmap() otherwise.

Affected Software

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

Vendor	Product	Versions
Linux	Linux	>= cb6ebbdffef2a888b95f121637cd1fad473919c6, < 01f2e0da8548f82d704b65b513026cfedc5f8962; >= cb6ebbdffef2a888b95f121637cd1fad473919c6, < b754d3a6d44c53d9853eba374d8a7ef279a9d00a; >= cb6ebbdffef2a888b95f121637cd1fad473919c6, < deaa2e3656937fbbe312f0ee2616c756c6e2511f; 91a5a48702e948e45df01a4f2fd54a0b0d0d6efb; >= 6.17.8, < 6.18
Linux	Linux	6.18

References

Timeline

Published: Sep 11, 2026
Last Modified: Sep 11, 2026
Status: Received

Frequently Asked Questions

What is CVE-2026-80934?

In the Linux kernel, the following vulnerability has been resolved: wifi: mt76: mt7996: fix TX DMA mapping leak for AddBA req frames mt7996/mt7992 hand the firmware a HW MAC-TXP for AddBA req action frames (MT_TXD7_MAC_TXD, set in mt7996_mac_write_txwi_80211()), but are otherwise FW-TXP devices. On tx free mt76_connac_txp_skb_unmap() therefore decodes the per-frame txp as a struct mt76_connac_fw_txp. For a MAC-TXP the fw_txp.nbuf byte aliases the AddBA TID word (MT_TXP1_TID_ADDBA), which is always zero, so the unmap loop runs zero times and the skb DMA mapping in buf[1] is never unmapped. buf[1].skip_unmap is set unconditionally, so the generic DMA-ring cleanup skips it as well. Each AddBA req therefore leaks one TX DMA mapping, roughly one per (re)association. With WED enabled these mappings are bounced through the WED swiotlb pool, so under continuous client reconnect churn the pool is exhausted after ~1-2 days, after which DMA mapping fails for WED, the WiFi MCU and other on-SoC consumers. Keep the deferred (token release) unmap that the design relies on, and add an mt7996-specific txp unmap that inspects MT_TXD7_MAC_TXD and unmaps buf[1] from the MAC-TXP layout for those frames, delegating to mt76_connac_txp_skb_unmap() otherwise.

How severe is CVE-2026-80934?

Severity scoring for CVE-2026-80934 is pending analysis.

How do I fix CVE-2026-80934?

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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