wifi: mt76: mt7996: fix TX DMA mapping leak for AddBA req frames

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-80934
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-11 20:18:57 UTC
Updated2026-09-11 20:18:57 UTC
DescriptionIn 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.

Risk And Classification

EPSS: 0.001660000 probability, percentile 0.061370000 (date 2026-09-12)

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected cb6ebbdffef2a888b95f121637cd1fad473919c6 01f2e0da8548f82d704b65b513026cfedc5f8962 git Not specified
CNA Linux Linux affected cb6ebbdffef2a888b95f121637cd1fad473919c6 b754d3a6d44c53d9853eba374d8a7ef279a9d00a git Not specified
CNA Linux Linux affected cb6ebbdffef2a888b95f121637cd1fad473919c6 deaa2e3656937fbbe312f0ee2616c756c6e2511f git Not specified
CNA Linux Linux affected 91a5a48702e948e45df01a4f2fd54a0b0d0d6efb git Not specified
CNA Linux Linux affected 6.17.8 6.18 semver Not specified
CNA Linux Linux affected 6.18 Not specified
CNA Linux Linux unaffected 6.18 semver Not specified
CNA Linux Linux unaffected 6.18.50 6.18.* semver Not specified
CNA Linux Linux unaffected 7.2.4 7.2.* semver Not specified
CNA Linux Linux unaffected 7.3-rc1 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/b754d3a6d44c53d9853eba374d8a7ef279a9d00a 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/deaa2e3656937fbbe312f0ee2616c756c6e2511f 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/01f2e0da8548f82d704b65b513026cfedc5f8962 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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