CVE-2026-93048 (GCVE-0-2026-93048)
Vulnerability from cvelistv5
Published
2026-09-17 16:10
Modified
2026-10-19 09:04
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: mtd: part: reject MTDPART_OFS_RETAIN in mtd_add_partition() mtd_add_partition() does not reject the special offset value MTDPART_OFS_RETAIN (-3), which leads to a WARN_ON in add_mtd_device() when called through the BLKPG ioctl on NAND devices. The RETAIN value depends on cur_offset being the end of the previous partition, but in the dynamic partition path cur_offset equals the offset argument itself, causing undefined behavior. Commit 5daa7b21496a ("mtd: prepare partition add and del functions for ioctl requests") introduced mtd_add_partition() and correctly rejected MTDPART_OFS_APPEND (-1) and MTDPART_OFS_NXTBLK (-2), since those special offsets rely on cur_offset tracking the previous partition's end. However, commit 1a31368bf92e ("mtd: add a flags for partitions which should just leave smth. after them") later added MTDPART_OFS_RETAIN (-3) for the static partition table path without updating mtd_add_partition() to also reject this value. With offset=-3 passed via BLKPG, the RETAIN size calculation in allocate_partition() underflows (parent_size - 0xFFFFFFFFFFFFFFFD = parent_size + 3). If the underflow result does not appear to leave enough space, allocate_partition() jumps to out_register via goto, skipping erasesize initialization. This results in erasesize=0, which triggers: WARN_ON((!mtd->erasesize || !master->_erase) && !(mtd->flags & MTD_NO_ERASE)) in add_mtd_device(). If the underflow result appears to leave enough space, a bogus partition size is calculated, but the "out of reach" sanity check catches the invalid offset and creates a disabled empty partition (offset=0, size=0) instead of returning an error. Fix this by adding MTDPART_OFS_RETAIN to the rejection list in mtd_add_partition(), consistent with the existing handling of APPEND and NXTBLK.
References
Impacted products
Vendor Product Version
Linux Linux Version: 1a31368bf92ef2a7da3ba379672c405bd2751df9
Version: 1a31368bf92ef2a7da3ba379672c405bd2751df9
Version: 1a31368bf92ef2a7da3ba379672c405bd2751df9
Version: 1a31368bf92ef2a7da3ba379672c405bd2751df9
Version: 1a31368bf92ef2a7da3ba379672c405bd2751df9
Version: 1a31368bf92ef2a7da3ba379672c405bd2751df9
Version: 1a31368bf92ef2a7da3ba379672c405bd2751df9
Version: 1a31368bf92ef2a7da3ba379672c405bd2751df9
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/mtd/mtdpart.c"
          ],
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          "vendor": "Linux",
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              "version": "0",
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              "version": "7.3",
              "versionType": "original_commit_for_fix"
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        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
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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\nmtd: part: reject MTDPART_OFS_RETAIN in mtd_add_partition()\n\nmtd_add_partition() does not reject the special offset value\nMTDPART_OFS_RETAIN (-3), which leads to a WARN_ON in\nadd_mtd_device() when called through the BLKPG ioctl on NAND\ndevices. The RETAIN value depends on cur_offset being the end of\nthe previous partition, but in the dynamic partition path\ncur_offset equals the offset argument itself, causing undefined\nbehavior.\n\nCommit 5daa7b21496a (\"mtd: prepare partition add and del functions\nfor ioctl requests\") introduced mtd_add_partition() and correctly\nrejected MTDPART_OFS_APPEND (-1) and MTDPART_OFS_NXTBLK (-2),\nsince those special offsets rely on cur_offset tracking the\nprevious partition\u0027s end. However, commit 1a31368bf92e (\"mtd: add a flags\nfor partitions which should just leave smth. after them\")\nlater added MTDPART_OFS_RETAIN (-3) for the static\npartition table path without updating mtd_add_partition() to\nalso reject this value.\n\nWith offset=-3 passed via BLKPG, the RETAIN size calculation in\nallocate_partition() underflows (parent_size - 0xFFFFFFFFFFFFFFFD\n= parent_size + 3). If the underflow result does not appear to\nleave enough space, allocate_partition() jumps to out_register via\ngoto, skipping erasesize initialization. This results in\nerasesize=0, which triggers:\n\nWARN_ON((!mtd-\u003eerasesize || !master-\u003e_erase) \u0026\u0026\n\t\t!(mtd-\u003eflags \u0026 MTD_NO_ERASE))\n\nin add_mtd_device(). If the underflow result appears to leave\nenough space, a bogus partition size is calculated, but the\n\"out of reach\" sanity check catches the invalid offset and\ncreates a disabled empty partition (offset=0, size=0) instead\nof returning an error.\n\nFix this by adding MTDPART_OFS_RETAIN to the rejection list in\nmtd_add_partition(), consistent with the existing handling of\nAPPEND and NXTBLK."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-19T09:04:43.363Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/701c3ae7273e1adc20db5d97c42e0139b479f16b"
        },
        {
          "url": "https://git.kernel.org/stable/c/6aaab2ace3f7b55733d904e5549acf8405f03642"
        },
        {
          "url": "https://git.kernel.org/stable/c/181c1bff940e7d3e34ca485d37e3cdbfe409203c"
        },
        {
          "url": "https://git.kernel.org/stable/c/a536eb57be58442b19398b2783071007ecfb1735"
        },
        {
          "url": "https://git.kernel.org/stable/c/e204e5c49a012f99638633fdbd773e3c86260053"
        },
        {
          "url": "https://git.kernel.org/stable/c/398aca2f90122d5abbabff1079deaeb885fe9e40"
        },
        {
          "url": "https://git.kernel.org/stable/c/c645f6dd1af2ecc70fd3578e141f2f71fa9e4eff"
        },
        {
          "url": "https://git.kernel.org/stable/c/b759d5bb6265419344ee9729fd0dc07ad85719d8"
        }
      ],
      "title": "mtd: part: reject MTDPART_OFS_RETAIN in mtd_add_partition()",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-93048",
    "datePublished": "2026-09-17T16:10:39.008Z",
    "dateReserved": "2026-09-17T15:57:05.658Z",
    "dateUpdated": "2026-10-19T09:04:43.363Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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