FKIE_CVE-2026-97569

Vulnerability from fkie_nvd - Published: 2026-09-25 11:17 - Updated: 2026-09-25 11:17
Severity
Summary
In the Linux kernel, the following vulnerability has been resolved: bnxt_en: Prevent queue stop with deferred completions When the driver receives a burst of packets, it can mark a BD with the NO_CMPL bit to defer completions. The expectation is that the last packet in the ring will have this bit unset and the completion generated by that packet will cleanup that packet and the ones preceding it. This helps to reduce the number of completions fired. The suppressed completions are controlled by the driver and the number of packets with suppressed completions scales with the size of the ring. SW USO packets, on the other hand, have an upper bound on the maximum number of BDs which can be consumed which does not scale with the ring size. So, for small rings it is possible that: a burst of packets is handed to the driver, the driver defers completions for all of the packets because the number of free descriptors stays above the threshold in the driver. Then, a USO packet arrives, but the number of BDs available is not enough and the USO code exits early. In this case, you end up in a state where the ring is full of packets with their completions suppressed, which can cause the queue to stop and never be restarted. Assuming default CONFIG_MAX_SKB_FRAGS, this is only possible for small rings (<= 457 descriptors, below the driver default value) when a burst of packets fills the ring, followed by a large USO packet that can't fit. For larger rings, the delta between the completion suppression threshold and the BDs required for SW USO is large enough that completions will fire and this case is unreachable. This issue was pointed out by Sashiko and while it seems fairly unlikely given that the queue size must be small to trigger this, it is indeed possible. Fix this by tracking the last BD which deferred completions and centralizing the logic for deciding when to ring the doorbell. The NO_CMPL bit is now cleared in bnxt_txr_db_kick(), so every doorbell site is covered, including the SW USO early exit. This guarantees the ring always ends in a BD which generates a completion to clean it and wake the queue.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/39b23c1c40e1f73d2b94a09282cc476af647e438
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/e33ce547c0cd40738d6bad23e5fc0539ee3e8f7d
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/net/ethernet/broadcom/bnxt/bnxt.c",
            "drivers/net/ethernet/broadcom/bnxt/bnxt.h",
            "drivers/net/ethernet/broadcom/bnxt/bnxt_gso.c",
            "drivers/net/ethernet/broadcom/bnxt/bnxt_gso.h"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "e33ce547c0cd40738d6bad23e5fc0539ee3e8f7d",
              "status": "affected",
              "version": "cc5d90667db81474ed7a92a1b2fa3daec5559307",
              "versionType": "git"
            },
            {
              "lessThan": "39b23c1c40e1f73d2b94a09282cc476af647e438",
              "status": "affected",
              "version": "cc5d90667db81474ed7a92a1b2fa3daec5559307",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "drivers/net/ethernet/broadcom/bnxt/bnxt.c",
            "drivers/net/ethernet/broadcom/bnxt/bnxt.h",
            "drivers/net/ethernet/broadcom/bnxt/bnxt_gso.c",
            "drivers/net/ethernet/broadcom/bnxt/bnxt_gso.h"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "7.1"
            },
            {
              "lessThan": "7.1",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.7",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3-rc3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbnxt_en: Prevent queue stop with deferred completions\n\nWhen the driver receives a burst of packets, it can mark a BD with the\nNO_CMPL bit to defer completions. The expectation is that the last\npacket in the ring will have this bit unset and the completion generated\nby that packet will cleanup that packet and the ones preceding it. This\nhelps to reduce the number of completions fired.\n\nThe suppressed completions are controlled by the driver and the number\nof packets with suppressed completions scales with the size of the ring.\nSW USO packets, on the other hand, have an upper bound on the maximum\nnumber of BDs which can be consumed which does not scale with the ring\nsize.\n\nSo, for small rings it is possible that: a burst of packets is handed to\nthe driver, the driver defers completions for all of the packets because\nthe number of free descriptors stays above the threshold in the driver.\nThen, a USO packet arrives, but the number of BDs available is not\nenough and the USO code exits early.\n\nIn this case, you end up in a state where the ring is full of packets\nwith their completions suppressed, which can cause the queue to stop and\nnever be restarted.\n\nAssuming default CONFIG_MAX_SKB_FRAGS, this is only possible for small\nrings (\u003c= 457 descriptors, below the driver default value) when\na burst of packets fills the ring, followed by a large USO packet that\ncan\u0027t fit. For larger rings, the delta between the completion\nsuppression threshold and the BDs required for SW USO is large enough\nthat completions will fire and this case is unreachable.\n\nThis issue was pointed out by Sashiko and while it seems fairly unlikely\ngiven that the queue size must be small to trigger this, it is indeed\npossible.\n\nFix this by tracking the last BD which deferred completions and\ncentralizing the logic for deciding when to ring the doorbell. The NO_CMPL\nbit is now cleared in bnxt_txr_db_kick(), so every doorbell site is\ncovered, including the SW USO early exit. This guarantees the ring always\nends in a BD which generates a completion to clean it and wake the queue."
    }
  ],
  "id": "CVE-2026-97569",
  "lastModified": "2026-09-25T11:17:07.570",
  "metrics": {},
  "published": "2026-09-25T11:17:07.570",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/39b23c1c40e1f73d2b94a09282cc476af647e438"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/e33ce547c0cd40738d6bad23e5fc0539ee3e8f7d"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}



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