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.