CVE-2025-40143 (GCVE-0-2025-40143)
Vulnerability from cvelistv5
Published
2025-11-12 10:23
Modified
2025-11-12 10:23
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: bpf: dont report verifier bug for missing bpf_scc_visit on speculative path Syzbot generated a program that triggers a verifier_bug() call in maybe_exit_scc(). maybe_exit_scc() assumes that, when called for a state with insn_idx in some SCC, there should be an instance of struct bpf_scc_visit allocated for that SCC. Turns out the assumption does not hold for speculative execution paths. See example in the next patch. maybe_scc_exit() is called from update_branch_counts() for states that reach branch count of zero, meaning that path exploration for a particular path is finished. Path exploration can finish in one of three ways: a. Verification error is found. In this case, update_branch_counts() is called only for non-speculative paths. b. Top level BPF_EXIT is reached. Such instructions are never a part of an SCC, so compute_scc_callchain() in maybe_scc_exit() will return false, and maybe_scc_exit() will return early. c. A checkpoint is reached and matched. Checkpoints are created by is_state_visited(), which calls maybe_enter_scc(), which allocates bpf_scc_visit instances for checkpoints within SCCs. Hence, for non-speculative symbolic execution paths, the assumption still holds: if maybe_scc_exit() is called for a state within an SCC, bpf_scc_visit instance must exist. This patch removes the verifier_bug() call for speculative paths.
References
Impacted products
Vendor Product Version
Linux Linux Version: c9e31900b54cadf5398dfb838c0a63effa1defec
Version: c9e31900b54cadf5398dfb838c0a63effa1defec
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "kernel/bpf/verifier.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
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              "status": "affected",
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              "versionType": "git"
            },
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              "versionType": "git"
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          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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            },
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              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.17.*",
              "status": "unaffected",
              "version": "6.17.3",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "6.18-rc1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.17.3",
                  "versionStartIncluding": "6.17",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18-rc1",
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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\nbpf: dont report verifier bug for missing bpf_scc_visit on speculative path\n\nSyzbot generated a program that triggers a verifier_bug() call in\nmaybe_exit_scc(). maybe_exit_scc() assumes that, when called for a\nstate with insn_idx in some SCC, there should be an instance of struct\nbpf_scc_visit allocated for that SCC. Turns out the assumption does\nnot hold for speculative execution paths. See example in the next\npatch.\n\nmaybe_scc_exit() is called from update_branch_counts() for states that\nreach branch count of zero, meaning that path exploration for a\nparticular path is finished. Path exploration can finish in one of\nthree ways:\na. Verification error is found. In this case, update_branch_counts()\n   is called only for non-speculative paths.\nb. Top level BPF_EXIT is reached. Such instructions are never a part of\n   an SCC, so compute_scc_callchain() in maybe_scc_exit() will return\n   false, and maybe_scc_exit() will return early.\nc. A checkpoint is reached and matched. Checkpoints are created by\n   is_state_visited(), which calls maybe_enter_scc(), which allocates\n   bpf_scc_visit instances for checkpoints within SCCs.\n\nHence, for non-speculative symbolic execution paths, the assumption\nstill holds: if maybe_scc_exit() is called for a state within an SCC,\nbpf_scc_visit instance must exist.\n\nThis patch removes the verifier_bug() call for speculative paths."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2025-11-12T10:23:25.489Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/3861e7c4324aa20a632fb74eb3904114f6afdb57"
        },
        {
          "url": "https://git.kernel.org/stable/c/a3c73d629ea1373af3c0c954d41fd1af555492e3"
        }
      ],
      "title": "bpf: dont report verifier bug for missing bpf_scc_visit on speculative path",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2025-40143",
    "datePublished": "2025-11-12T10:23:25.489Z",
    "dateReserved": "2025-04-16T07:20:57.175Z",
    "dateUpdated": "2025-11-12T10:23:25.489Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "nvd": "{\"cve\":{\"id\":\"CVE-2025-40143\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2025-11-12T11:15:44.130\",\"lastModified\":\"2025-11-12T16:19:12.850\",\"vulnStatus\":\"Awaiting Analysis\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nbpf: dont report verifier bug for missing bpf_scc_visit on speculative path\\n\\nSyzbot generated a program that triggers a verifier_bug() call in\\nmaybe_exit_scc(). maybe_exit_scc() assumes that, when called for a\\nstate with insn_idx in some SCC, there should be an instance of struct\\nbpf_scc_visit allocated for that SCC. Turns out the assumption does\\nnot hold for speculative execution paths. See example in the next\\npatch.\\n\\nmaybe_scc_exit() is called from update_branch_counts() for states that\\nreach branch count of zero, meaning that path exploration for a\\nparticular path is finished. Path exploration can finish in one of\\nthree ways:\\na. Verification error is found. In this case, update_branch_counts()\\n   is called only for non-speculative paths.\\nb. Top level BPF_EXIT is reached. Such instructions are never a part of\\n   an SCC, so compute_scc_callchain() in maybe_scc_exit() will return\\n   false, and maybe_scc_exit() will return early.\\nc. A checkpoint is reached and matched. Checkpoints are created by\\n   is_state_visited(), which calls maybe_enter_scc(), which allocates\\n   bpf_scc_visit instances for checkpoints within SCCs.\\n\\nHence, for non-speculative symbolic execution paths, the assumption\\nstill holds: if maybe_scc_exit() is called for a state within an SCC,\\nbpf_scc_visit instance must exist.\\n\\nThis patch removes the verifier_bug() call for speculative paths.\"}],\"metrics\":{},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/3861e7c4324aa20a632fb74eb3904114f6afdb57\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/a3c73d629ea1373af3c0c954d41fd1af555492e3\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}"
  }
}


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