{
  "schema_version": "1.6.1",
  "id": "RPI-CVE-2026-98027",
  "modified": "2026-10-09T11:39:44Z",
  "upstream": [
    "CVE-2026-98027"
  ],
  "published": "2026-09-25T10:24:31Z",
  "summary": "net: dsa: mv88e6xxx: bound the policy rule dump by the caller's buffer size",
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: dsa: mv88e6xxx: bound the policy rule dump by the caller's buffer size\n\nmv88e6xxx_get_rxnfc() uses rxnfc->rule_cnt as the write index while\ndumping the policy IDR, clobbering the input value before it has been\nlooked at.  That input is the number of entries the caller had room for.\nETHTOOL_GRXCLSRLALL requires no CAP_NET_ADMIN and the ioctl sizes the\nbuffer from the rule_cnt userspace passes in, so once an admin has\ninstalled policy rules any user can ask for fewer slots than there are\nrules and run off the end of the allocation.  A rule_cnt of 0 leaves the\nbuffer pointer NULL and the walk dereferences it.\n\nCount into a local so the caller's limit survives the walk, and stop with\n-EMSGSIZE once it is reached.",
  "severity": [
    {
      "type": "CVSS_V3",
      "score": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H"
    }
  ],
  "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-2026-98027"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/7e4bfc5f0b66feb22cba821303fc25ca22cd0887"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/01124cd2cf4b71755b1130ac82d78dcfbd5d69e3"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/609c4378f212cf580aae02250f1146caf63d873f"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/c5b5c52b6524c9fb50def2260baac745c095ec3a"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/44cd4674d9aa5bdf793b8a8b481c9e8536ed6070"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/7a683c2b062810bca203e41866389daf387c235b"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/cda5ac8fe8ac8e80b1703ebb8c4250726fc19739"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/b1fffc273112e7284c5b705e186b43b5770cd3d5"
    }
  ],
  "database_specific": {
    "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git",
    "upstream_modified": "2026-10-03T11:04:09Z",
    "severity": {
      "source": "kernel CNA",
      "cvss_v3_score": 7.0,
      "cvss_v3_severity": "High",
      "scenario": "AV:L - The overflow is reached only through the local SIOCETHTOOL ioctl: dev_ethtool() -> ethtool_get_rxnfc() -> dsa_user_get_rxnfc() -> mv88e6xxx_get_rxnfc(ETHTOOL_GRXCLSRLALL). The bad input is the rule_cnt field of the ethtool_rxnfc struct the user passes in. No network packet reaches this path.\nAC:H - The OOB write only happens if policy rules already exist in chip->policies for that DSA port. Those are installed by an admin via ETHTOOL_SRXCLSRLINS, which needs CAP_NET_ADMIN over the hardware port. The attacker can't create that state. Once rules exist, a small rule_cnt triggers it deterministically.\nPR:L - dev_ethtool() lists ETHTOOL_GRXCLSRLALL among the commands exempt from the ns_capable(CAP_NET_ADMIN) check. Any unprivileged local user who can see the mv88e6xxx user port in their netns can issue the ioctl.\nUI:N - The attacker makes the ioctl call and picks rule_cnt themselves. No other user has to do anything.\nS:U - The corruption hits the kernel heap in the same kernel that runs the attacker's ioctl. No VM, IOMMU or other authority boundary is crossed.\nC:H - ethtool_get_rxnfc() sizes rule_buf with kcalloc(rule_cnt, 4) from the user's value. The driver then overwrites rxnfc->rule_cnt with the real rule count, so ethtool_rxnfc_copy_to_user() copies that many u32s from the undersized buffer, reading past the slab object into userspace. The same heap corruption can also be groomed to leak more.\nI:H - mv88e6xxx_get_rxnfc() writes rule_locs[rxnfc->rule_cnt++] = id for every rule on the port with no bound, so u32 IDs go past a kmalloc object whose size and cache the attacker chose via rule_cnt. That heap OOB write can corrupt neighbouring objects.\nA:H - With rule_cnt=0, ethtool_get_rxnfc() passes a NULL rule_buf and the IDR walk writes through it, oopsing the kernel on demand. Larger overflows corrupt slab memory and can panic the system. Either can be repeated."
    }
  }
}