{
  "schema_version": "1.6.1",
  "id": "RPI-CVE-2026-93830",
  "modified": "2026-10-07T17:22:01Z",
  "upstream": [
    "CVE-2026-93830"
  ],
  "published": "2026-09-24T16:08:25Z",
  "summary": "net: stmmac: xgmac2: disable RBUE in default RX interrupt mask",
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: stmmac: xgmac2: disable RBUE in default RX interrupt mask\n\nEnabling the RX Buffer Unavailable (RBUE) interrupt is counterproductive\nand can trigger a MAC interrupt storm under heavy RX pressure. When the\nDMA runs out of RX descriptors it fires RBUE continuously until software\nrefills the ring.\n\nHowever, RBUE is redundant: the normal RX completion interrupt (RIE)\nalready triggers NAPI, which processes completed descriptors and refills\nthe ring, causing the DMA to resume. The RBUE handler itself only sets\nhandle_rx - the same outcome as RIE.\n\nOn Agilex5 under heavy RX pressure, the MAC interrupt (which includes\nRBUE) was observed firing 1,821,811,555 times against only 2,618,627\nactual RX completions - a ~695x ratio - confirming the severity of the\nstorm.\n\nRBUE does not provide OOM recovery. If page_pool is exhausted,\nstmmac_rx_refill() cannot advance the DMA tail pointer, the DMA stays\nsuspended, and RBUE fires again on the next NAPI completion - a storm\nwith no forward progress. This patch trades that storm for a clean\nstall with the same RX outcome. Proper OOM recovery is a pre-existing\ngap outside the scope of this fix.\n\nNote: as a consequence of disabling RBUE, the rx_buf_unav_irq ethtool\ncounter will always read 0 on XGMAC2 devices. This behaviour is already\ninconsistent across DWMAC core versions.\n\nRemove RBUE from XGMAC_DMA_INT_DEFAULT_EN and XGMAC_DMA_INT_DEFAULT_RX\nto prevent the interrupt storm while keeping normal RX handling intact.",
  "affected": [
    {
      "package": {
        "ecosystem": "Raspberry Pi OS:12",
        "name": "linux"
      },
      "versions": [
        "1:6.1.47-1+rpt4"
      ],
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-2712",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v6",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v7",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v7l",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v8",
            "binary_version": "1:6.1.47-1+rpt4"
          }
        ]
      },
      "database_specific": {
        "per_version": {
          "1:6.1.47-1+rpt4": {
            "linux_commit": "655fc658a15ae7a6f37103754adb39ba52a9a14e",
            "upstream_version": "6.1.47",
            "assessment": "commit ancestry (strak rule)",
            "upstream_fixed": "6.1.189",
            "compiled_filter": false
          }
        }
      }
    }
  ],
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-93830"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/8c9d57b5dc098b84631d0b3559c84c499ea2170a"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/7a10e54e42a8f73a8d731f5a281fc06bb41b9250"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/6b3b91433d5f4eae6865cdaa96f40cd67849e1f6"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/74dbb85a6a254b5fc1f265a6cd61b2ba9d9221d7"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/0b1a5d3647ce07c27a9fffefc11a8cbf7d7b25ce"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/87e2826ed2058747ddf014c082569a46bfadd96b"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/d3265c19b35d036bba327b36b5366bee76b0157c"
    }
  ],
  "database_specific": {
    "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git",
    "upstream_modified": "2026-10-03T11:04:09Z"
  }
}