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net: stmmac: xgmac2: disable RBUE in default RX interrupt mask

Type: advisorySource: Official CVE List1 source record

In the Linux kernel, the following vulnerability has been resolved: net: stmmac: xgmac2: disable RBUE in default RX interrupt mask Enabling the RX Buffer Unavailable (RBUE) interrupt is counterproductive and can trigger a MAC interrupt storm under heavy RX pressure. When the DMA runs out of RX descriptors it fires RBUE continuously until software refills the ring. However, RBUE is redundant: the normal RX completion interrupt (RIE) already triggers NAPI, which processes completed descriptors and refills the ring, causing the DMA to resume. The RBUE handler itself only sets handle_rx - the same outcome as RIE. On Agilex5 under heavy RX pressure, the MAC interrupt (which includes RBUE) was observed firing 1,821,811,555 times against only 2,618,627 actual RX completions - a ~695x ratio - confirming the severity of the storm. RBUE does not provide OOM recovery. If page_pool is exhausted, stmmac_rx_refill() cannot advance the DMA tail pointer, the DMA stays suspended, and RBUE fires again on the next NAPI completion - a storm with no forward progress. This patch trades that storm for a clean stall with the same RX outcome. Proper OOM recovery is a pre-existing gap outside the scope of this fix. Note: as a consequence of disabling RBUE, the rx_buf_unav_irq ethtool counter will always read 0 on XGMAC2 devices. This behaviour is already inconsistent across DWMAC core versions. Remove RBUE from XGMAC_DMA_INT_DEFAULT_EN and XGMAC_DMA_INT_DEFAULT_RX to prevent the interrupt storm while

Announced Source revision 1
Original source ↗

CVE-2026-93830

Primary source · Revision 1

Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.

Security context

Source reference: cve:CVE-2026-93830

Linux

Source reference: /containers/cna/affected/0/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
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Linux

Source reference: /containers/cna/affected/1/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Structured affected-version data

Original package identities and version rules from this source.

[
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "d6ddfacd95c79d43465d4a85dffb1c9beca343a9",
        "lessThan": "8c9d57b5dc098b84631d0b3559c84c499ea2170a",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "d6ddfacd95c79d43465d4a85dffb1c9beca343a9",
        "lessThan": "7a10e54e42a8f73a8d731f5a281fc06bb41b9250",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "d6ddfacd95c79d43465d4a85dffb1c9beca343a9",
        "lessThan": "6b3b91433d5f4eae6865cdaa96f40cd67849e1f6",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "d6ddfacd95c79d43465d4a85dffb1c9beca343a9",
        "lessThan": "74dbb85a6a254b5fc1f265a6cd61b2ba9d9221d7",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "d6ddfacd95c79d43465d4a85dffb1c9beca343a9",
        "lessThan": "0b1a5d3647ce07c27a9fffefc11a8cbf7d7b25ce",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "d6ddfacd95c79d43465d4a85dffb1c9beca343a9",
        "lessThan": "87e2826ed2058747ddf014c082569a46bfadd96b",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "d6ddfacd95c79d43465d4a85dffb1c9beca343a9",
        "lessThan": "d3265c19b35d036bba327b36b5366bee76b0157c",
        "versionType": "git"
      }
    ],
    "programFiles": [
      "drivers/net/ethernet/stmicro/stmmac/dwxgmac2.h"
    ],
    "defaultStatus": "unaffected"
  },
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "4.19"
      },
      {
        "status": "unaffected",
        "version": "0",
        "lessThan": "4.19",
        "versionType": "semver"
      },
      {
        "status": "unaffected",
        "version": "5.10.271",
        "versionType": "semver",
        "lessThanOrEqual": "5.10.*"
      },
      {
        "status": "unaffected",
        "version": "5.15.222",
        "versionType": "semver",
        "lessThanOrEqual": "5.15.*"
      },
      {
        "status": "unaffected",
        "version": "6.1.189",
        "versionType": "semver",
        "lessThanOrEqual": "6.1.*"
      },
      {
        "status": "unaffected",
        "version": "6.6.158",
        "versionType": "semver",
        "lessThanOrEqual": "6.6.*"
      },
      {
        "status": "unaffected",
        "version": "6.12.111",
        "versionType": "semver",
        "lessThanOrEqual": "6.12.*"
      },
      {
        "status": "unaffected",
        "version": "6.18.53",
        "versionType": "semver",
        "lessThanOrEqual": "6.18.*"
      },
      {
        "status": "unaffected",
        "version": "7.2",
        "versionType": "original_commit_for_fix",
        "lessThanOrEqual": "*"
      }
    ],
    "programFiles": [
      "drivers/net/ethernet/stmicro/stmmac/dwxgmac2.h"
    ],
    "defaultStatus": "affected"
  }
]
Related CVEs
CVE-2026-93830

Source reference: /cveMetadata/cveId

Publisher severity

high

Source reference: /containers/cna/metrics

Event
#8300 · Revision 1
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Publisher date
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