CVE-2026-99079 (GCVE-0-2026-99079)
Vulnerability from cvelistv5
Published
2026-10-23 12:23
Modified
2026-10-24 14:10
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: net/mlx5e: Prevent stale XSK buffer release on refill retry When an XDP redirect to an AF_XDP socket fails because its RX ring is full, the XSK core frees the buffer. During the subsequent batched refill of a legacy cyclic RQ, mlx5e also releases the WQE's XSK buffer before allocating a replacement. If that refill succeeds only partially, a WQE left without a replacement retains its old buffer pointer. The buffer can meanwhile be allocated to another WQE. A later refill retry can then free the live buffer through the stale pointer and publish the same UMEM frame twice. Mark the WQE as released immediately after the driver-side free. The flag is already cleared when a replacement buffer is assigned, so refill retries no longer release stale pointers. The failure is silent and produces no kernel warning or splat. A standalone legacy cyclic-RQ zero-copy libxsk reproducer, using 64-byte UDP traffic offered at 12 Mpps, detected it: stock stopped after 2,854,914 packets in 4.094 seconds, with 4,542 xdp_rx_ring_full events and 64 ownership/double-publication errors. With this change it processed 356,904,225 packets in 30 seconds despite 571,405 xdp_rx_ring_full events, with no ownership or data errors.
Impacted products
Vendor Product Version
Linux Linux Version: 3f93f82988bc6b4104314bf9aa485d47fbb7e241
Version: 3f93f82988bc6b4104314bf9aa485d47fbb7e241
Version: 3f93f82988bc6b4104314bf9aa485d47fbb7e241
Version: 3f93f82988bc6b4104314bf9aa485d47fbb7e241
Version: 3f93f82988bc6b4104314bf9aa485d47fbb7e241
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{
  "containers": {
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          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/net/ethernet/mellanox/mlx5/core/en_rx.c"
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          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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              "version": "6.4"
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              "status": "unaffected",
              "version": "0",
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              "status": "unaffected",
              "version": "6.6.160",
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              "status": "unaffected",
              "version": "6.12.113",
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            },
            {
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              "status": "unaffected",
              "version": "6.18.57",
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            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.11",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
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                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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                  "vulnerable": true
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                  "versionEndExcluding": "6.12.113",
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              "negate": false,
              "operator": "OR"
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/mlx5e: Prevent stale XSK buffer release on refill retry\n\nWhen an XDP redirect to an AF_XDP socket fails because its RX ring is\nfull, the XSK core frees the buffer. During the subsequent batched refill\nof a legacy cyclic RQ, mlx5e also releases the WQE\u0027s XSK buffer before\nallocating a replacement. If that refill succeeds only partially, a WQE\nleft without a replacement retains its old buffer pointer.\n\nThe buffer can meanwhile be allocated to another WQE. A later refill\nretry can then free the live buffer through the stale pointer and publish\nthe same UMEM frame twice.\n\nMark the WQE as released immediately after the driver-side free. The flag\nis already cleared when a replacement buffer is assigned, so refill\nretries no longer release stale pointers.\n\nThe failure is silent and produces no kernel warning or splat. A\nstandalone legacy cyclic-RQ zero-copy libxsk reproducer, using 64-byte UDP\ntraffic offered at 12 Mpps, detected it: stock stopped after 2,854,914\npackets in 4.094 seconds, with 4,542 xdp_rx_ring_full events and 64\nownership/double-publication errors. With this change it processed\n356,904,225 packets in 30 seconds despite 571,405 xdp_rx_ring_full events,\nwith no ownership or data errors."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 9.8,
            "baseSeverity": "CRITICAL",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - UDP datagrams reaching mlx5 drive mlx5e_completion_event() -\u003e mlx5e_napi_poll() -\u003e mlx5e_poll_rx_cq()/XDP redirect, then mlx5e_napi_xsk_post() -\u003e mlx5e_post_rx_wqes() -\u003e patched mlx5e_xsk_free_rx_wqe(); sustained routable traffic fills the XSK RX ring and triggers stale release.\nAC:L - A sender can sustain small-packet traffic until __xsk_rcv_zc() reports RX-ring-full and mlx5e_xsk_alloc_rx_wqes_batched() refills only part of the missing WQEs; retries are deterministic and require no uncontrolled race or memory layout.\nPR:N - The NIC-CQE/NAPI receive path contains no capability or authentication check; xsk_create()\u0027s CAP_NET_RAW check applies to victim-side AF_XDP provisioning, while the remote UDP sender needs no privileges.\nUI:N - Once the zero-copy XSK pool and XDP redirect are active, xsk_rcv_zc() failure, mlx5e_napi_xsk_post(), and refill retries occur automatically as packets arrive, without further victim action.\nS:U - mlx5e_xsk_free_rx_wqe() corrupts the host kernel\u0027s xsk_buff_pool and mlx5 receive state without crossing a VM, IOMMU, or other security-authority boundary.\nC:H - Duplicate xdp_buff_xsk ownership lets repeated successful __xsk_rcv_zc() calls invoke unbounded xp_release(); in unaligned-UMEM mode, free_heads_cnt can write kernel pointers past the flexible free_heads[] array, yielding heap corruption exploitable for arbitrary disclosure.\nI:H - The duplicate WQEs can make xp_release() write beyond free_heads[], while xp_get_xskb() later trusts pointers popped through the corrupted count; this supplies out-of-bounds and corrupted-pointer write primitives capable of control-flow hijacking.\nA:H - The free_heads[] overflow or a bogus xskb consumed by xp_get_xskb() can oops or panic; additionally, the dma_dev_need_sync refill path can store NULL on allocation failure and have the stale retry pass it to xsk_buff_free()."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-24T14:10:21.247Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/32bbb870078d467479965c21bbc4960c57eea208"
        },
        {
          "url": "https://git.kernel.org/stable/c/34d1db2b18e1c1d189e34dd51923e031815f88e3"
        },
        {
          "url": "https://git.kernel.org/stable/c/639522e5056cade578a324acfa993ec6c9f7f5dc"
        },
        {
          "url": "https://git.kernel.org/stable/c/655f47477054d19de3b138840be229a1a4490d0c"
        },
        {
          "url": "https://git.kernel.org/stable/c/e01620844c5c88b6fcf819d171df8e3976a0e76f"
        }
      ],
      "title": "net/mlx5e: Prevent stale XSK buffer release on refill retry",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-99079",
    "datePublished": "2026-10-23T12:23:26.458Z",
    "dateReserved": "2026-09-25T10:25:14.389Z",
    "dateUpdated": "2026-10-24T14:10:21.247Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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