mm/slab: return NULL early from kmalloc_nolock() in NMI on UP

{
  "id": "a190ae49f36e002016e794687f96b27b284c2d8c27041000eaabbdaf25401cef",
  "url": "https://osv.dev/vulnerability/CVE-2026-46029",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "mm/slab: return NULL early from kmalloc_nolock() in NMI on UP",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: mm/slab: return NULL early from kmalloc_nolock() in NMI on UP On UP kernels (!CONFIG_SMP), spin_trylock() is a no-op that unconditionally succeeds even when the lock is already held. As a result, kmalloc_nolock() called from NMI context can re-enter the slab allocator and acquire n->list_lock that the interrupted context is already holding, corrupting slab state. With CONFIG_DEBUG_SPINLOCK on UP, the following BUG is triggered with the slub_kunit test module: BUG: spinlock trylock failure on UP on CPU#0, kunit_try_catch/243 [...] Call Trace: dump_stack_lvl+0x3f/0x60 do_raw_spin_trylock+0x41/0x50 _raw_spin_trylock+0x24/0x50 get_from_partial_node+0x120/0x4d0 ___slab_alloc+0x8a/0x4c0 kmalloc_nolock_noprof+0x164/0x310 [...] Fix this by returning NULL early when invoked from NMI on a UP kernel.",
    "evidence": "osv:CVE-2026-46029",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.18.27",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "7.0.4",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "high",
    "structured": {
      "id": "CVE-2026-46029",
      "aliases": [
        "CVE-2026-46029"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "af92793e52c3a99b828ed4bdd277fd3e11c18d08"
                },
                {
                  "fixed": "a8d95d274be241ad21f6523bf2d6ba0d7d7e46b7"
                },
                {
                  "fixed": "d66553204a15bdb257d9ef8aca1e12f5fbb910b2"
                },
                {
                  "fixed": "5b31044e649e3e54c2caef135c09b371c2fbcd08"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-46029.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.18.0"
                },
                {
                  "fixed": "6.18.27"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.19.0"
                },
                {
                  "fixed": "7.0.4"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-46029.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:43.182252152Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/5b31044e649e3e54c2caef135c09b371c2fbcd08",
        "https://git.kernel.org/stable/c/a8d95d274be241ad21f6523bf2d6ba0d7d7e46b7",
        "https://git.kernel.org/stable/c/d66553204a15bdb257d9ef8aca1e12f5fbb910b2",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/46xxx/CVE-2026-46029.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-46029",
        "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
      ],
      "provider_metadata": {
        "cna_assigner": "Linux",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/46xxx/CVE-2026-46029.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-46029",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 510688,
  "published_at": "2026-05-27T12:56:38.376+00:00"
}