CVE-2026-89962 (GCVE-0-2026-89962)
Vulnerability from cvelistv5
Published
2026-09-16 10:32
Modified
2026-10-21 12:49
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: powerpc/kexec_file: Prevent kexec range truncation Sashiko AI review pointed out the following issue. The __merge_memory_ranges() function incorrectly handles overlapping memory ranges when merging them. Although sort_memory_ranges() sorts all ranges by their start address in ascending order beforehand, the merge logic remains defective in two ways: 1. It compares the current range's start against the previous element (i-1) instead of the running target index (idx) 2. It unconditionally overwrites 'ranges[idx].end' with 'ranges[i].end'. This logic flaw leads to critical memory truncation when a larger memory range completely subsumes subsequent smaller ranges. For example, consider a sorted input array with three ranges: Range A (idx=0): [0x1000 - 0x9000] Range B (i=1): [0x2000 - 0x5000] (completely inside Range A) Range C (i=2): [0x6000 - 0x8000] (completely inside Range A) 1. When i=1 (Range B): ranges[1].start (0x2000) <= ranges[0].end + 1 (0x9001) is TRUE. The code executes: ranges[0].end = ranges[1].end, which erroneously shrinks Range A's end from 0x9000 down to 0x5000. 2. When i=2 (Range C): ranges[2].start (0x6000) <= ranges[1].end + 1 (0x5001) is FALSE. The code falls into the else block, creating a broken new range. As a result, valid memory fragments [0x5001 - 0x5fff] and [0x8001 - 0x9000] are completely lost from the kexec exclude lists, potentially allowing the crash kernel to overwrite active memory, causing data corruption or crashes. Fix this by ensuring the start of the current range is compared against the end of the active merged range (idx), and use max() to safely prevent the outer boundary from being truncated.
References
Impacted products
Vendor Product Version
Linux Linux Version: 180adfc532a83c1d74146449f7385f767d4b8059
Version: 180adfc532a83c1d74146449f7385f767d4b8059
Version: 180adfc532a83c1d74146449f7385f767d4b8059
Version: 180adfc532a83c1d74146449f7385f767d4b8059
Version: 180adfc532a83c1d74146449f7385f767d4b8059
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "arch/powerpc/kexec/ranges.c"
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          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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              "status": "affected",
              "version": "5.9"
            },
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              "version": "0",
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              "status": "unaffected",
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              "version": "6.12.110",
              "versionType": "semver"
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              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.51",
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              "status": "unaffected",
              "version": "7.2.5",
              "versionType": "semver"
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            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.160",
                  "versionStartIncluding": "5.9",
                  "vulnerable": true
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                  "vulnerable": true
                },
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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\npowerpc/kexec_file: Prevent kexec range truncation\n\nSashiko AI review pointed out the following issue.\n\nThe __merge_memory_ranges() function incorrectly handles overlapping\nmemory ranges when merging them. Although sort_memory_ranges() sorts all\nranges by their start address in ascending order beforehand, the merge\nlogic remains defective in two ways:\n\n1. It compares the current range\u0027s start against the previous element (i-1)\n   instead of the running target index (idx)\n\n2. It unconditionally overwrites \u0027ranges[idx].end\u0027 with \u0027ranges[i].end\u0027.\n\nThis logic flaw leads to critical memory truncation when a larger memory\nrange completely subsumes subsequent smaller ranges.\n\nFor example, consider a sorted input array with three ranges:\n  Range A (idx=0): [0x1000 - 0x9000]\n  Range B (i=1):   [0x2000 - 0x5000] (completely inside Range A)\n  Range C (i=2):   [0x6000 - 0x8000] (completely inside Range A)\n\n1. When i=1 (Range B):\n   ranges[1].start (0x2000) \u003c= ranges[0].end + 1 (0x9001) is TRUE.\n   The code executes: ranges[0].end = ranges[1].end, which erroneously\n   shrinks Range A\u0027s end from 0x9000 down to 0x5000.\n\n2. When i=2 (Range C):\n   ranges[2].start (0x6000) \u003c= ranges[1].end + 1 (0x5001) is FALSE.\n   The code falls into the else block, creating a broken new range.\n\nAs a result, valid memory fragments [0x5001 - 0x5fff] and [0x8001 - 0x9000]\nare completely lost from the kexec exclude lists, potentially allowing\nthe crash kernel to overwrite active memory, causing data corruption\nor crashes.\n\nFix this by ensuring the start of the current range is compared against the\nend of the active merged range (idx), and use max() to safely prevent the\nouter boundary from being truncated."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-21T12:49:16.173Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/ffbdc2a3834a3e47bac7236a71bbc82b45c83832"
        },
        {
          "url": "https://git.kernel.org/stable/c/9ef63622e6cee588ea4b763a6afc87065254b36a"
        },
        {
          "url": "https://git.kernel.org/stable/c/da88a2a2119e4fd0e8919a7a2448682f574e1545"
        },
        {
          "url": "https://git.kernel.org/stable/c/c4cb547f26d9b73b489c5278d0c8db837c5a174f"
        },
        {
          "url": "https://git.kernel.org/stable/c/fa40f9dbdd4af53e7445d9135b5b207eb8adf372"
        }
      ],
      "title": "powerpc/kexec_file: Prevent kexec range truncation",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-89962",
    "datePublished": "2026-09-16T10:32:44.623Z",
    "dateReserved": "2026-09-11T19:38:34.778Z",
    "dateUpdated": "2026-10-21T12:49:16.173Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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