CVE-2026-46029 (GCVE-0-2026-46029)
Vulnerability from cvelistv5
Published
2026-05-27 12:56
Modified
2026-08-05 12:29
Severity ?
7.0 (High) - CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
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: <NMI> 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 [...] </NMI> Fix this by returning NULL early when invoked from NMI on a UP kernel.
References
Impacted products
Vendor Product Version
Linux Linux Version: af92793e52c3a99b828ed4bdd277fd3e11c18d08
Version: af92793e52c3a99b828ed4bdd277fd3e11c18d08
Version: af92793e52c3a99b828ed4bdd277fd3e11c18d08
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{
  "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": "a8d95d274be241ad21f6523bf2d6ba0d7d7e46b7",
              "status": "affected",
              "version": "af92793e52c3a99b828ed4bdd277fd3e11c18d08",
              "versionType": "git"
            },
            {
              "lessThan": "d66553204a15bdb257d9ef8aca1e12f5fbb910b2",
              "status": "affected",
              "version": "af92793e52c3a99b828ed4bdd277fd3e11c18d08",
              "versionType": "git"
            },
            {
              "lessThan": "5b31044e649e3e54c2caef135c09b371c2fbcd08",
              "status": "affected",
              "version": "af92793e52c3a99b828ed4bdd277fd3e11c18d08",
              "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",
              "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",
                  "versionStartIncluding": "6.18",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm/slab: return NULL early from kmalloc_nolock() in NMI on UP\n\nOn UP kernels (!CONFIG_SMP), spin_trylock() is a no-op that\nunconditionally succeeds even when the lock is already held. As a\nresult, kmalloc_nolock() called from NMI context can re-enter the slab\nallocator and acquire n-\u003elist_lock that the interrupted context is\nalready holding, corrupting slab state.\n\nWith CONFIG_DEBUG_SPINLOCK on UP, the following BUG is triggered with\nthe slub_kunit test module:\n\n  BUG: spinlock trylock failure on UP on CPU#0, kunit_try_catch/243\n  [...]\n  Call Trace:\n   \u003cNMI\u003e\n   dump_stack_lvl+0x3f/0x60\n   do_raw_spin_trylock+0x41/0x50\n   _raw_spin_trylock+0x24/0x50\n   get_from_partial_node+0x120/0x4d0\n   ___slab_alloc+0x8a/0x4c0\n   kmalloc_nolock_noprof+0x164/0x310\n   [...]\n   \u003c/NMI\u003e\n\nFix this by returning NULL early when invoked from NMI on a UP kernel."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - The only callers reaching NMI-context kmalloc_nolock() are local BPF programs (perf events) or in-kernel module code; there is no remote/network path to this allocator routine.\nAC:H - The bug only manifests on rare non-default uniprocessor (!CONFIG_SMP) kernels, and additionally requires the NMI to fire during the narrow window in which the interrupted context holds n-\u003elist_lock \u2014 both conditions are beyond the attacker\u0027s control.\nPR:L - Running code in NMI context that calls kmalloc_nolock() requires attaching a BPF program to a hardware perf event (CAP_BPF/CAP_PERFMON), which are sub-root capabilities delegable to confined tracing/profiling service accounts rather than full root.\nUI:N - Triggering the NMI-context allocation requires no action from any other user or victim.\nS:U - The slab-state corruption stays within the kernel\u0027s own security authority; no cross-boundary (VM/IOMMU) escape is involved.\nC:H - Re-entrant slab list/freelist corruption is a powerful primitive that can produce overlapping allocations and be leveraged for kernel memory disclosure.\nI:H - Corruption of SLUB partial-list/freelist metadata is a well-known basis for arbitrary-write primitives and control-flow hijacking.\nA:H - The corrupted slab state (or the DEBUG_SPINLOCK BUG) leads to kernel oops/panic, a full availability loss."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:29:13.390Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/a8d95d274be241ad21f6523bf2d6ba0d7d7e46b7"
        },
        {
          "url": "https://git.kernel.org/stable/c/d66553204a15bdb257d9ef8aca1e12f5fbb910b2"
        },
        {
          "url": "https://git.kernel.org/stable/c/5b31044e649e3e54c2caef135c09b371c2fbcd08"
        }
      ],
      "title": "mm/slab: return NULL early from kmalloc_nolock() in NMI on UP",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-46029",
    "datePublished": "2026-05-27T12:56:38.376Z",
    "dateReserved": "2026-05-13T15:03:33.093Z",
    "dateUpdated": "2026-08-05T12:29:13.390Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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