CVE-2025-68795 (GCVE-0-2025-68795)
Vulnerability from cvelistv5
Published
2026-01-13 15:29
Modified
2026-02-09 08:33
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: ethtool: Avoid overflowing userspace buffer on stats query The ethtool -S command operates across three ioctl calls: ETHTOOL_GSSET_INFO for the size, ETHTOOL_GSTRINGS for the names, and ETHTOOL_GSTATS for the values. If the number of stats changes between these calls (e.g., due to device reconfiguration), userspace's buffer allocation will be incorrect, potentially leading to buffer overflow. Drivers are generally expected to maintain stable stat counts, but some drivers (e.g., mlx5, bnx2x, bna, ksz884x) use dynamic counters, making this scenario possible. Some drivers try to handle this internally: - bnad_get_ethtool_stats() returns early in case stats.n_stats is not equal to the driver's stats count. - micrel/ksz884x also makes sure not to write anything beyond stats.n_stats and overflow the buffer. However, both use stats.n_stats which is already assigned with the value returned from get_sset_count(), hence won't solve the issue described here. Change ethtool_get_strings(), ethtool_get_stats(), ethtool_get_phy_stats() to not return anything in case of a mismatch between userspace's size and get_sset_size(), to prevent buffer overflow. The returned n_stats value will be equal to zero, to reflect that nothing has been returned. This could result in one of two cases when using upstream ethtool, depending on when the size change is detected: 1. When detected in ethtool_get_strings(): # ethtool -S eth2 no stats available 2. When detected in get stats, all stats will be reported as zero. Both cases are presumably transient, and a subsequent ethtool call should succeed. Other than the overflow avoidance, these two cases are very evident (no output/cleared stats), which is arguably better than presenting incorrect/shifted stats. I also considered returning an error instead of a "silent" response, but that seems more destructive towards userspace apps. Notes: - This patch does not claim to fix the inherent race, it only makes sure that we do not overflow the userspace buffer, and makes for a more predictable behavior. - RTNL lock is held during each ioctl, the race window exists between the separate ioctl calls when the lock is released. - Userspace ethtool always fills stats.n_stats, but it is likely that these stats ioctls are implemented in other userspace applications which might not fill it. The added code checks that it's not zero, to prevent any regressions.
References
Impacted products
Vendor Product Version
Linux Linux Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
Version: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
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{
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          "product": "Linux",
          "programFiles": [
            "net/ethtool/ioctl.c"
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nethtool: Avoid overflowing userspace buffer on stats query\n\nThe ethtool -S command operates across three ioctl calls:\nETHTOOL_GSSET_INFO for the size, ETHTOOL_GSTRINGS for the names, and\nETHTOOL_GSTATS for the values.\n\nIf the number of stats changes between these calls (e.g., due to device\nreconfiguration), userspace\u0027s buffer allocation will be incorrect,\npotentially leading to buffer overflow.\n\nDrivers are generally expected to maintain stable stat counts, but some\ndrivers (e.g., mlx5, bnx2x, bna, ksz884x) use dynamic counters, making\nthis scenario possible.\n\nSome drivers try to handle this internally:\n- bnad_get_ethtool_stats() returns early in case stats.n_stats is not\n  equal to the driver\u0027s stats count.\n- micrel/ksz884x also makes sure not to write anything beyond\n  stats.n_stats and overflow the buffer.\n\nHowever, both use stats.n_stats which is already assigned with the value\nreturned from get_sset_count(), hence won\u0027t solve the issue described\nhere.\n\nChange ethtool_get_strings(), ethtool_get_stats(),\nethtool_get_phy_stats() to not return anything in case of a mismatch\nbetween userspace\u0027s size and get_sset_size(), to prevent buffer\noverflow.\nThe returned n_stats value will be equal to zero, to reflect that\nnothing has been returned.\n\nThis could result in one of two cases when using upstream ethtool,\ndepending on when the size change is detected:\n1. When detected in ethtool_get_strings():\n    # ethtool -S eth2\n    no stats available\n\n2. When detected in get stats, all stats will be reported as zero.\n\nBoth cases are presumably transient, and a subsequent ethtool call\nshould succeed.\n\nOther than the overflow avoidance, these two cases are very evident (no\noutput/cleared stats), which is arguably better than presenting\nincorrect/shifted stats.\nI also considered returning an error instead of a \"silent\" response, but\nthat seems more destructive towards userspace apps.\n\nNotes:\n- This patch does not claim to fix the inherent race, it only makes sure\n  that we do not overflow the userspace buffer, and makes for a more\n  predictable behavior.\n\n- RTNL lock is held during each ioctl, the race window exists between\n  the separate ioctl calls when the lock is released.\n\n- Userspace ethtool always fills stats.n_stats, but it is likely that\n  these stats ioctls are implemented in other userspace applications\n  which might not fill it. The added code checks that it\u0027s not zero,\n  to prevent any regressions."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-02-09T08:33:42.945Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/3df375a1e75483b7d973c3cc2e46aa374db8428b"
        },
        {
          "url": "https://git.kernel.org/stable/c/f9dc0f45d2cd0189ce666288a29d2cc32c2e44d5"
        },
        {
          "url": "https://git.kernel.org/stable/c/4afcb985355210e1688560dc47e64b94dad35d71"
        },
        {
          "url": "https://git.kernel.org/stable/c/ca9983bc3a1189bd72f9ae449d925a66b2616326"
        },
        {
          "url": "https://git.kernel.org/stable/c/7bea09f60f2ad5d232e2db8f1c14e850fd3fd416"
        },
        {
          "url": "https://git.kernel.org/stable/c/4066b5b546293f44cd6d0e84ece6e3ee7ff27093"
        },
        {
          "url": "https://git.kernel.org/stable/c/7b07be1ff1cb6c49869910518650e8d0abc7d25f"
        }
      ],
      "title": "ethtool: Avoid overflowing userspace buffer on stats query",
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  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2025-68795",
    "datePublished": "2026-01-13T15:29:06.217Z",
    "dateReserved": "2025-12-24T10:30:51.041Z",
    "dateUpdated": "2026-02-09T08:33:42.945Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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