Vulnerability-Lookup

FKIE_CVE-2026-45990

Vulnerability from fkie_nvd - Published: 2026-05-27 14:17 - Updated: 2026-05-27 14:48

Severity

Summary

In the Linux kernel, the following vulnerability has been resolved: slub: fix data loss and overflow in krealloc() Commit 2cd8231796b5 ("mm/slub: allow to set node and align in k[v]realloc") introduced the ability to force a reallocation if the original object does not satisfy new alignment or NUMA node, even when the object is being shrunk. This introduced two bugs in the reallocation fallback path: 1. Data loss during NUMA migration: The jump to 'alloc_new' happens before 'ks' and 'orig_size' are initialized. As a result, the memcpy() in the 'alloc_new' block would copy 0 bytes into the new allocation. 2. Buffer overflow during shrinking: When shrinking an object while forcing a new alignment, 'new_size' is smaller than the old size. However, the memcpy() used the old size ('orig_size ?: ks'), leading to an out-of-bounds write. The same overflow bug exists in the kvrealloc() fallback path, where the old bucket size ksize(p) is copied into the new buffer without being bounded by the new size. A simple reproducer: // e.g. add to lkdtm as KREALLOC_SHRINK_OVERFLOW while (1) { void *p = kmalloc(128, GFP_KERNEL); p = krealloc_node_align(p, 64, 256, GFP_KERNEL, NUMA_NO_NODE); kfree(p); } demonstrates the issue: ================================================================== BUG: KFENCE: out-of-bounds write in memcpy_orig+0x68/0x130 Out-of-bounds write at 0xffff8883ad757038 (120B right of kfence-#47): memcpy_orig+0x68/0x130 krealloc_node_align_noprof+0x1c8/0x340 lkdtm_KREALLOC_SHRINK_OVERFLOW+0x8c/0xc0 [lkdtm] lkdtm_do_action+0x3a/0x60 [lkdtm] ... kfence-#47: 0xffff8883ad756fc0-0xffff8883ad756fff, size=64, cache=kmalloc-64 allocated by task 316 on cpu 7 at 97.680481s (0.021813s ago): krealloc_node_align_noprof+0x19c/0x340 lkdtm_KREALLOC_SHRINK_OVERFLOW+0x8c/0xc0 [lkdtm] lkdtm_do_action+0x3a/0x60 [lkdtm] ... ================================================================== Fix it by moving the old size calculation to the top of __do_krealloc() and bounding all copy lengths by the new allocation size.

References

	URL	Tags
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/082a6d03a2d685a83a332666b500ad3966349588
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/38387ccc0fbe38d14fb4c2ad7ee1d7404e5e59fd
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/550fa6b5aabb096554536ac1e3ec96b76cbb35fd

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nslub: fix data loss and overflow in krealloc()\n\nCommit 2cd8231796b5 (\"mm/slub: allow to set node and align in\nk[v]realloc\") introduced the ability to force a reallocation if the\noriginal object does not satisfy new alignment or NUMA node, even when\nthe object is being shrunk.\n\nThis introduced two bugs in the reallocation fallback path:\n\n1. Data loss during NUMA migration: The jump to \u0027alloc_new\u0027 happens\n   before \u0027ks\u0027 and \u0027orig_size\u0027 are initialized. As a result, the\n   memcpy() in the \u0027alloc_new\u0027 block would copy 0 bytes into the new\n   allocation.\n\n2. Buffer overflow during shrinking: When shrinking an object while\n   forcing a new alignment, \u0027new_size\u0027 is smaller than the old size.\n   However, the memcpy() used the old size (\u0027orig_size ?: ks\u0027), leading\n   to an out-of-bounds write.\n\nThe same overflow bug exists in the kvrealloc() fallback path, where the\nold bucket size ksize(p) is copied into the new buffer without being\nbounded by the new size.\n\nA simple reproducer:\n\n\t// e.g. add to lkdtm as KREALLOC_SHRINK_OVERFLOW\n\twhile (1) {\n\t\tvoid *p = kmalloc(128, GFP_KERNEL);\n\t\tp = krealloc_node_align(p, 64, 256, GFP_KERNEL, NUMA_NO_NODE);\n\t\tkfree(p);\n\t}\n\ndemonstrates the issue:\n\n  ==================================================================\n  BUG: KFENCE: out-of-bounds write in memcpy_orig+0x68/0x130\n\n  Out-of-bounds write at 0xffff8883ad757038 (120B right of kfence-#47):\n   memcpy_orig+0x68/0x130\n   krealloc_node_align_noprof+0x1c8/0x340\n   lkdtm_KREALLOC_SHRINK_OVERFLOW+0x8c/0xc0 [lkdtm]\n   lkdtm_do_action+0x3a/0x60 [lkdtm]\n   ...\n\n  kfence-#47: 0xffff8883ad756fc0-0xffff8883ad756fff, size=64, cache=kmalloc-64\n\n  allocated by task 316 on cpu 7 at 97.680481s (0.021813s ago):\n   krealloc_node_align_noprof+0x19c/0x340\n   lkdtm_KREALLOC_SHRINK_OVERFLOW+0x8c/0xc0 [lkdtm]\n   lkdtm_do_action+0x3a/0x60 [lkdtm]\n   ...\n  ==================================================================\n\nFix it by moving the old size calculation to the top of __do_krealloc()\nand bounding all copy lengths by the new allocation size."
    }
  ],
  "id": "CVE-2026-45990",
  "lastModified": "2026-05-27T14:48:03.013",
  "metrics": {},
  "published": "2026-05-27T14:17:16.527",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/082a6d03a2d685a83a332666b500ad3966349588"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/38387ccc0fbe38d14fb4c2ad7ee1d7404e5e59fd"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/550fa6b5aabb096554536ac1e3ec96b76cbb35fd"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Awaiting Analysis"
}

CVE-2026-45990 (GCVE-0-2026-45990)

Vulnerability from cvelistv5 – Published: 2026-05-27 12:55 – Updated: 2026-05-27 12:55

Title

slub: fix data loss and overflow in krealloc()

Summary

Severity

No CVSS data available.

Assigner

Linux

References

3 references

URL	Tags
https://git.kernel.org/stable/c/38387ccc0fbe38d14…
https://git.kernel.org/stable/c/550fa6b5aabb09655…
https://git.kernel.org/stable/c/082a6d03a2d685a83…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 2cd8231796b5e7133b1c3d66ad7d2a3c42c97258 , < 38387ccc0fbe38d14fb4c2ad7ee1d7404e5e59fd (git) Affected: 2cd8231796b5e7133b1c3d66ad7d2a3c42c97258 , < 550fa6b5aabb096554536ac1e3ec96b76cbb35fd (git) Affected: 2cd8231796b5e7133b1c3d66ad7d2a3c42c97258 , < 082a6d03a2d685a83a332666b500ad3966349588 (git)
Linux	Linux	Affected: 6.18 Unaffected: 0 , < 6.18 (semver) Unaffected: 6.18.27 , ≤ 6.18.* (semver) Unaffected: 7.0.4 , ≤ 7.0.* (semver) Unaffected: 7.1-rc1 , ≤ * (original_commit_for_fix)

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "mm/slub.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "38387ccc0fbe38d14fb4c2ad7ee1d7404e5e59fd",
              "status": "affected",
              "version": "2cd8231796b5e7133b1c3d66ad7d2a3c42c97258",
              "versionType": "git"
            },
            {
              "lessThan": "550fa6b5aabb096554536ac1e3ec96b76cbb35fd",
              "status": "affected",
              "version": "2cd8231796b5e7133b1c3d66ad7d2a3c42c97258",
              "versionType": "git"
            },
            {
              "lessThan": "082a6d03a2d685a83a332666b500ad3966349588",
              "status": "affected",
              "version": "2cd8231796b5e7133b1c3d66ad7d2a3c42c97258",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "mm/slub.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.18"
            },
            {
              "lessThan": "6.18",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.27",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.0.*",
              "status": "unaffected",
              "version": "7.0.4",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.1-rc1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.27",
                  "versionStartIncluding": "6.18",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.0.4",
                  "versionStartIncluding": "6.18",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.1-rc1",
                  "versionStartIncluding": "6.18",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nslub: fix data loss and overflow in krealloc()\n\nCommit 2cd8231796b5 (\"mm/slub: allow to set node and align in\nk[v]realloc\") introduced the ability to force a reallocation if the\noriginal object does not satisfy new alignment or NUMA node, even when\nthe object is being shrunk.\n\nThis introduced two bugs in the reallocation fallback path:\n\n1. Data loss during NUMA migration: The jump to \u0027alloc_new\u0027 happens\n   before \u0027ks\u0027 and \u0027orig_size\u0027 are initialized. As a result, the\n   memcpy() in the \u0027alloc_new\u0027 block would copy 0 bytes into the new\n   allocation.\n\n2. Buffer overflow during shrinking: When shrinking an object while\n   forcing a new alignment, \u0027new_size\u0027 is smaller than the old size.\n   However, the memcpy() used the old size (\u0027orig_size ?: ks\u0027), leading\n   to an out-of-bounds write.\n\nThe same overflow bug exists in the kvrealloc() fallback path, where the\nold bucket size ksize(p) is copied into the new buffer without being\nbounded by the new size.\n\nA simple reproducer:\n\n\t// e.g. add to lkdtm as KREALLOC_SHRINK_OVERFLOW\n\twhile (1) {\n\t\tvoid *p = kmalloc(128, GFP_KERNEL);\n\t\tp = krealloc_node_align(p, 64, 256, GFP_KERNEL, NUMA_NO_NODE);\n\t\tkfree(p);\n\t}\n\ndemonstrates the issue:\n\n  ==================================================================\n  BUG: KFENCE: out-of-bounds write in memcpy_orig+0x68/0x130\n\n  Out-of-bounds write at 0xffff8883ad757038 (120B right of kfence-#47):\n   memcpy_orig+0x68/0x130\n   krealloc_node_align_noprof+0x1c8/0x340\n   lkdtm_KREALLOC_SHRINK_OVERFLOW+0x8c/0xc0 [lkdtm]\n   lkdtm_do_action+0x3a/0x60 [lkdtm]\n   ...\n\n  kfence-#47: 0xffff8883ad756fc0-0xffff8883ad756fff, size=64, cache=kmalloc-64\n\n  allocated by task 316 on cpu 7 at 97.680481s (0.021813s ago):\n   krealloc_node_align_noprof+0x19c/0x340\n   lkdtm_KREALLOC_SHRINK_OVERFLOW+0x8c/0xc0 [lkdtm]\n   lkdtm_do_action+0x3a/0x60 [lkdtm]\n   ...\n  ==================================================================\n\nFix it by moving the old size calculation to the top of __do_krealloc()\nand bounding all copy lengths by the new allocation size."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-05-27T12:55:42.572Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/38387ccc0fbe38d14fb4c2ad7ee1d7404e5e59fd"
        },
        {
          "url": "https://git.kernel.org/stable/c/550fa6b5aabb096554536ac1e3ec96b76cbb35fd"
        },
        {
          "url": "https://git.kernel.org/stable/c/082a6d03a2d685a83a332666b500ad3966349588"
        }
      ],
      "title": "slub: fix data loss and overflow in krealloc()",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-45990",
    "datePublished": "2026-05-27T12:55:42.572Z",
    "dateReserved": "2026-05-13T15:03:33.091Z",
    "dateUpdated": "2026-05-27T12:55:42.572Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

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FKIE_CVE-2026-45990

CVE-2026-45990 (GCVE-0-2026-45990)

Tags

Sightings

Nomenclature