CVE-2026-80934 (GCVE-0-2026-80934)
Vulnerability from cvelistv5
Published
2026-09-11 19:42
Modified
2026-10-19 08:45
Severity ?
Summary
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.
References
Impacted products
Vendor Product Version
Linux Linux Version: cb6ebbdffef2a888b95f121637cd1fad473919c6
Version: cb6ebbdffef2a888b95f121637cd1fad473919c6
Version: cb6ebbdffef2a888b95f121637cd1fad473919c6
Version: 91a5a48702e948e45df01a4f2fd54a0b0d0d6efb
Version: 6.17.8   ≤
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/net/wireless/mediatek/mt76/mt7996/mac.c"
          ],
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          "product": "Linux",
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          "vendor": "Linux",
          "versions": [
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              "version": "6.18"
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              "status": "unaffected",
              "version": "0",
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              "status": "unaffected",
              "version": "6.18.50",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.4",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
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        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
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              "cpeMatch": [
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                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.50",
                  "versionStartIncluding": "6.18",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nwifi: mt76: mt7996: fix TX DMA mapping leak for AddBA req frames\n\nmt7996/mt7992 hand the firmware a HW MAC-TXP for AddBA req action frames\n(MT_TXD7_MAC_TXD, set in mt7996_mac_write_txwi_80211()), but are otherwise\nFW-TXP devices. On tx free mt76_connac_txp_skb_unmap() therefore decodes\nthe per-frame txp as a struct mt76_connac_fw_txp. For a MAC-TXP the\nfw_txp.nbuf byte aliases the AddBA TID word (MT_TXP1_TID_ADDBA), which is\nalways zero, so the unmap loop runs zero times and the skb DMA mapping in\nbuf[1] is never unmapped. buf[1].skip_unmap is set unconditionally, so the\ngeneric DMA-ring cleanup skips it as well.\n\nEach AddBA req therefore leaks one TX DMA mapping, roughly one per\n(re)association. With WED enabled these mappings are bounced through the\nWED swiotlb pool, so under continuous client reconnect churn the pool is\nexhausted after ~1-2 days, after which DMA mapping fails for WED, the WiFi\nMCU and other on-SoC consumers.\n\nKeep the deferred (token release) unmap that the design relies on, and add\nan mt7996-specific txp unmap that inspects MT_TXD7_MAC_TXD and unmaps\nbuf[1] from the MAC-TXP layout for those frames, delegating to\nmt76_connac_txp_skb_unmap() otherwise."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-19T08:45:18.030Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/01f2e0da8548f82d704b65b513026cfedc5f8962"
        },
        {
          "url": "https://git.kernel.org/stable/c/b754d3a6d44c53d9853eba374d8a7ef279a9d00a"
        },
        {
          "url": "https://git.kernel.org/stable/c/deaa2e3656937fbbe312f0ee2616c756c6e2511f"
        }
      ],
      "title": "wifi: mt76: mt7996: fix TX DMA mapping leak for AddBA req frames",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-80934",
    "datePublished": "2026-09-11T19:42:08.494Z",
    "dateReserved": "2026-08-26T14:34:25.802Z",
    "dateUpdated": "2026-10-19T08:45:18.030Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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