mmc: core: Add validation for host-provided max_segs

{
  "id": "3c66a475383f00b8e2decbe423e646b290e37bcfd728bd6fc3deff152a6448bc",
  "url": "https://www.cve.org/CVERecord?id=CVE-2026-98884",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "mmc: core: Add validation for host-provided max_segs",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: mmc: core: Add validation for host-provided max_segs The max_segs field is of type unsigned short, and if a host driver sets an excessively large value, it may be truncated to zero. This can cause mmc_alloc_sg() to call kmalloc_objs() with a zero size allocation request, which leads to undefined behavior. Under the SLUB allocator, kmalloc(0) returns a special pointer (ZERO_SIZE_PTR). The subsequent 'if (sg)' check will evaluate to true, and sg_init_table() will then attempt to access invalid memory, resulting in a crash: dwmmc_rockchip 2a310000.mmc: Successfully tuned phase to 133 mmc1: new UHS-I speed SDR104 SDHC card at address aaaa Unable to handle kernel paging request at virtual address 0000001ffffffff0 Mem abort info: ESR = 0x0000000096000004 EC = 0x25: DABT (current EL), IL = 32 bits SET = 0, FnV = 0 EA = 0, S1PTW = 0 FSC = 0x04: level 0 translation fault Data abort info: ISV = 0, ISS = 0x00000004, ISS2 = 0x00000000 CM = 0, WnR = 0, TnD = 0, TagAccess = 0 GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0 user pgtable: 4k pages, 48-bit VAs, pgdp=0000000102c88000 [0000001ffffffff0] pgd=0000000000000000, p4d=0000000000000000 Internal error: Oops: 0000000096000004 [#1] SMP Modules linked in: CPU: 2 UID: 0 PID: 102 Comm: kworker/2:1 Not tainted 7.0.0-rc6-next-20260331-00013-g4d93c25963c5-dirty #80 PREEMPT Hardware name: Rockchip RK3576 EVB V10 Board (DT) Workqueue: events_freezable mmc_rescan pstate: 80000005 (Nzc",
    "evidence": "cve:CVE-2026-98884",
    "products": [
      {
        "name": {
          "value": "Linux",
          "evidence": "/containers/cna/affected/0/product"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": []
      },
      {
        "name": {
          "value": "Linux",
          "evidence": "/containers/cna/affected/1/product"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2026-98884",
      "aliases": [
        "CVE-2026-98884"
      ],
      "metrics": [],
      "affected": [
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "05e5b136459b11cd9559370d5756719e08074fe0",
              "lessThan": "03f5a16ec85beebabd5ab5e67ac1527f87908ded",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "05e5b136459b11cd9559370d5756719e08074fe0",
              "lessThan": "c465608bd25d7f8565be7817a6a36a5d69f8aa14",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "05e5b136459b11cd9559370d5756719e08074fe0",
              "lessThan": "a8283f7d93f0d9336b15618b9665279ff6944319",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "05e5b136459b11cd9559370d5756719e08074fe0",
              "lessThan": "9cca3c0c1472d6204ef8a78a6e7b3afe9610b22e",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "05e5b136459b11cd9559370d5756719e08074fe0",
              "lessThan": "b037c2f7794aa01ee2a00e43c29645fd2dd2dfb9",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "05e5b136459b11cd9559370d5756719e08074fe0",
              "lessThan": "3e0483e93a8be320f70a1ff68d835f7f015af311",
              "versionType": "git"
            }
          ],
          "programFiles": [
            "drivers/mmc/core/queue.c"
          ],
          "defaultStatus": "unaffected"
        },
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "2.6.24"
            },
            {
              "status": "unaffected",
              "version": "0",
              "lessThan": "2.6.24",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "5.15.222",
              "versionType": "semver",
              "lessThanOrEqual": "5.15.*"
            },
            {
              "status": "unaffected",
              "version": "6.1.189",
              "versionType": "semver",
              "lessThanOrEqual": "6.1.*"
            },
            {
              "status": "unaffected",
              "version": "6.6.158",
              "versionType": "semver",
              "lessThanOrEqual": "6.6.*"
            },
            {
              "status": "unaffected",
              "version": "6.12.111",
              "versionType": "semver",
              "lessThanOrEqual": "6.12.*"
            },
            {
              "status": "unaffected",
              "version": "6.18.53",
              "versionType": "semver",
              "lessThanOrEqual": "6.18.*"
            },
            {
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ],
          "programFiles": [
            "drivers/mmc/core/queue.c"
          ],
          "defaultStatus": "affected"
        }
      ],
      "modified": "2026-10-26T06:56:08.177Z",
      "provider": "cve",
      "references": [
        "https://git.kernel.org/stable/c/03f5a16ec85beebabd5ab5e67ac1527f87908ded",
        "https://git.kernel.org/stable/c/c465608bd25d7f8565be7817a6a36a5d69f8aa14",
        "https://git.kernel.org/stable/c/a8283f7d93f0d9336b15618b9665279ff6944319",
        "https://git.kernel.org/stable/c/9cca3c0c1472d6204ef8a78a6e7b3afe9610b22e",
        "https://git.kernel.org/stable/c/b037c2f7794aa01ee2a00e43c29645fd2dd2dfb9",
        "https://git.kernel.org/stable/c/3e0483e93a8be320f70a1ff68d835f7f015af311"
      ],
      "provider_metadata": {
        "cna": {
          "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
          "shortName": "Linux",
          "dateUpdated": "2026-10-26T06:56:08.177Z"
        }
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-98884",
        "evidence": "/cveMetadata/cveId"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-cve",
  "document_id": 263342,
  "published_at": "2026-10-23T11:37:39.893+00:00"
}