GHSA-499P-P84W-R6W8

Vulnerability from github – Published: 2026-07-25 12:31 – Updated: 2026-07-27 06:30
VLAI
Details

In the Linux kernel, the following vulnerability has been resolved:

partitions: aix: bound the pp_count scan to the ppe array

aix_partition() reads the physical volume descriptor into a fixed-size struct pvd and then scans its physical-partition-extent array:

int numpps = be16_to_cpu(pvd->pp_count);
...
for (i = 0; i < numpps; i += 1) {
    struct ppe *p = pvd->ppe + i;
    ...
    lp_ix = be16_to_cpu(p->lp_ix);

pvd points at a single kmalloc()'d struct pvd whose ppe[] member holds a fixed ARRAY_SIZE(pvd->ppe) (1016) entries, but the loop runs up to the on-disk pp_count. pp_count is an unvalidated __be16 read straight from the descriptor, so a crafted AIX image with pp_count larger than 1016 drives the loop to read pvd->ppe[i] past the end of the allocation (up to 65535 entries, ~2 MB out of bounds).

The partition scan runs without mounting anything, when a block device with a crafted AIX/IBM partition table appears (an attacker-supplied image attached with losetup -P, or a device auto-scanned by udev), via msdos_partition() -> aix_partition().

Clamp the scan to the number of entries the ppe[] array can hold.

Severity
7.1 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
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{
  "affected": [],
  "aliases": [
    "CVE-2026-64318"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-07-25T10:17:13Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\npartitions: aix: bound the pp_count scan to the ppe array\n\naix_partition() reads the physical volume descriptor into a fixed-size\nstruct pvd and then scans its physical-partition-extent array:\n\n\tint numpps = be16_to_cpu(pvd-\u003epp_count);\n\t...\n\tfor (i = 0; i \u003c numpps; i += 1) {\n\t\tstruct ppe *p = pvd-\u003eppe + i;\n\t\t...\n\t\tlp_ix = be16_to_cpu(p-\u003elp_ix);\n\npvd points at a single kmalloc()\u0027d struct pvd whose ppe[] member holds a\nfixed ARRAY_SIZE(pvd-\u003eppe) (1016) entries, but the loop runs up to the\non-disk pp_count.  pp_count is an unvalidated __be16 read straight from\nthe descriptor, so a crafted AIX image with pp_count larger than 1016\ndrives the loop to read pvd-\u003eppe[i] past the end of the allocation (up\nto 65535 entries, ~2 MB out of bounds).\n\nThe partition scan runs without mounting anything, when a block device\nwith a crafted AIX/IBM partition table appears (an attacker-supplied\nimage attached with losetup -P, or a device auto-scanned by udev), via\nmsdos_partition() -\u003e aix_partition().\n\nClamp the scan to the number of entries the ppe[] array can hold.",
  "id": "GHSA-499p-p84w-r6w8",
  "modified": "2026-07-27T06:30:32Z",
  "published": "2026-07-25T12:31:31Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-64318"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/09861651617ba0fec089e8b9477439e68398c110"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/2dc0bfd2fe355fb930de63c2f2eb8ced8570c579"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/44f37ee92fdcd377c41bdf6a31cdd8cc7d4c410e"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/4671bb74bba05fdd4acf670a35758c29e8c97b83"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/5eacdb1967378f5e5591cd27a2d8cdee2df1a599"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/b5e9c09309e18fd9839ad007c238120353ca0cc4"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/ce93228e2193a17d2c58b656e439bb39fe5c3af8"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/fd94a779020f2ecc8b2607f4c20b34acb1763b9a"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H",
      "type": "CVSS_V3"
    }
  ]
}



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