CVE-2025-39904 (GCVE-0-2025-39904)

Vulnerability from cvelistv5 – Published: 2025-10-01 07:44 – Updated: 2026-05-11 21:38
VLAI
Title
arm64: kexec: initialize kexec_buf struct in load_other_segments()
Summary
In the Linux kernel, the following vulnerability has been resolved: arm64: kexec: initialize kexec_buf struct in load_other_segments() Patch series "kexec: Fix invalid field access". The kexec_buf structure was previously declared without initialization. commit bf454ec31add ("kexec_file: allow to place kexec_buf randomly") added a field that is always read but not consistently populated by all architectures. This un-initialized field will contain garbage. This is also triggering a UBSAN warning when the uninitialized data was accessed: ------------[ cut here ]------------ UBSAN: invalid-load in ./include/linux/kexec.h:210:10 load of value 252 is not a valid value for type '_Bool' Zero-initializing kexec_buf at declaration ensures all fields are cleanly set, preventing future instances of uninitialized memory being used. An initial fix was already landed for arm64[0], and this patchset fixes the problem on the remaining arm64 code and on riscv, as raised by Mark. Discussions about this problem could be found at[1][2]. This patch (of 3): The kexec_buf structure was previously declared without initialization. commit bf454ec31add ("kexec_file: allow to place kexec_buf randomly") added a field that is always read but not consistently populated by all architectures. This un-initialized field will contain garbage. This is also triggering a UBSAN warning when the uninitialized data was accessed: ------------[ cut here ]------------ UBSAN: invalid-load in ./include/linux/kexec.h:210:10 load of value 252 is not a valid value for type '_Bool' Zero-initializing kexec_buf at declaration ensures all fields are cleanly set, preventing future instances of uninitialized memory being used.
Severity
5.5 (Medium)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
SSVC
Exploitation: none Automatable: no Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-01-14 19:30 UTC
CWE
  • CWE-908 - Use of Uninitialized Resource
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: bf454ec31add6790f6cdc88328e38901fcbbade6 , < 340cc9a3bd30b25edaf6a9708d41b5f2c10a054a (git)
Affected: bf454ec31add6790f6cdc88328e38901fcbbade6 , < 04d3cd43700a2d0fe4bfb1012a8ec7f2e34a3507 (git)
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Linux Linux Affected: 6.16
Unaffected: 0 , < 6.16 (semver)
Unaffected: 6.16.8 , ≤ 6.16.* (semver)
Unaffected: 6.17 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
Show details on NVD website
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                  "status": "unaffected",
                  "version": "6.17",
                  "versionType": "original_commit_for_fix"
                }
              ]
            }
          ],
          "cpeApplicability": [
            {
              "nodes": [
                {
                  "cpeMatch": [
                    {
                      "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                      "versionEndExcluding": "6.16.8",
                      "versionStartIncluding": "6.16",
                      "vulnerable": true
                    },
                    {
                      "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                      "versionEndExcluding": "6.17",
                      "versionStartIncluding": "6.16",
                      "vulnerable": true
                    }
                  ],
                  "negate": false,
                  "operator": "OR"
                }
              ]
            }
          ],
          "descriptions": [
            {
              "lang": "en",
              "value": "In the Linux kernel, the following vulnerability has been resolved:\n\narm64: kexec: initialize kexec_buf struct in load_other_segments()\n\nPatch series \"kexec: Fix invalid field access\".\n\nThe kexec_buf structure was previously declared without initialization. \ncommit bf454ec31add (\"kexec_file: allow to place kexec_buf randomly\")\nadded a field that is always read but not consistently populated by all\narchitectures.  This un-initialized field will contain garbage.\n\nThis is also triggering a UBSAN warning when the uninitialized data was\naccessed:\n\n\t------------[ cut here ]------------\n\tUBSAN: invalid-load in ./include/linux/kexec.h:210:10\n\tload of value 252 is not a valid value for type \u0027_Bool\u0027\n\nZero-initializing kexec_buf at declaration ensures all fields are cleanly\nset, preventing future instances of uninitialized memory being used.\n\nAn initial fix was already landed for arm64[0], and this patchset fixes\nthe problem on the remaining arm64 code and on riscv, as raised by Mark.\n\nDiscussions about this problem could be found at[1][2].\n\n\nThis patch (of 3):\n\nThe kexec_buf structure was previously declared without initialization.\ncommit bf454ec31add (\"kexec_file: allow to place kexec_buf randomly\")\nadded a field that is always read but not consistently populated by all\narchitectures. This un-initialized field will contain garbage.\n\nThis is also triggering a UBSAN warning when the uninitialized data was\naccessed:\n\n\t------------[ cut here ]------------\n\tUBSAN: invalid-load in ./include/linux/kexec.h:210:10\n\tload of value 252 is not a valid value for type \u0027_Bool\u0027\n\nZero-initializing kexec_buf at declaration ensures all fields are\ncleanly set, preventing future instances of uninitialized memory being\nused."
            }
          ],
          "providerMetadata": {
            "dateUpdated": "2025-10-01T07:44:27.739Z",
            "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "shortName": "Linux"
          },
          "references": [
            {
              "url": "https://git.kernel.org/stable/c/340cc9a3bd30b25edaf6a9708d41b5f2c10a054a"
            },
            {
              "url": "https://git.kernel.org/stable/c/04d3cd43700a2d0fe4bfb1012a8ec7f2e34a3507"
            }
          ],
          "title": "arm64: kexec: initialize kexec_buf struct in load_other_segments()",
          "x_generator": {
            "engine": "bippy-1.2.0"
          }
        }
      },
      "cveMetadata": {
        "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "assignerShortName": "Linux",
        "cveId": "CVE-2025-39904",
        "datePublished": "2025-10-01T07:44:27.739Z",
        "dateReserved": "2025-04-16T07:20:57.146Z",
        "dateUpdated": "2026-01-14T19:33:14.694Z",
        "state": "PUBLISHED"
      },
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}



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