CVE-2026-74740 (GCVE-0-2026-74740)
Vulnerability from cvelistv5
Published
2026-08-26 14:36
Modified
2026-08-26 14:36
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: net/sched: act_api: fix TOCTOU NULL deref on a->goto_chain tcf_action_exec() handles TC_ACT_GOTO_CHAIN by first checking rcu_access_pointer(a->goto_chain) and then calling tcf_action_goto_chain_exec(), which does a second, independent rcu_dereference_bh(a->goto_chain) read and immediately dereferences chain->filter_chain. A concurrent tcf_action_set_ctrlact() (e.g. the gact replace path) can clear a->goto_chain between the two reads, so the second read returns NULL and tcf_action_goto_chain_exec() dereferences NULL. Fix the race by doing a single rcu_dereference_bh() read of a->goto_chain in tcf_action_exec(), checking it once for NULL, and passing the resulting chain pointer into tcf_action_goto_chain_exec(). This turns the split check/use into a single check/use on one value.
References
Impacted products
Vendor Product Version
Linux Linux Version: ee3bbfe806cdb46b02cda63626cb50a7a7b19fc5
Version: ee3bbfe806cdb46b02cda63626cb50a7a7b19fc5
Version: ee3bbfe806cdb46b02cda63626cb50a7a7b19fc5
Version: ee3bbfe806cdb46b02cda63626cb50a7a7b19fc5
Version: ee3bbfe806cdb46b02cda63626cb50a7a7b19fc5
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/sched/act_api.c"
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          "programFiles": [
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          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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              "status": "affected",
              "version": "5.1"
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              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
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              "versionType": "semver"
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              "version": "6.18.46",
              "versionType": "semver"
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              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.10",
              "versionType": "semver"
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            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
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                {
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              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: act_api: fix TOCTOU NULL deref on a-\u003egoto_chain\n\ntcf_action_exec() handles TC_ACT_GOTO_CHAIN by first checking\nrcu_access_pointer(a-\u003egoto_chain) and then calling\ntcf_action_goto_chain_exec(), which does a second, independent\nrcu_dereference_bh(a-\u003egoto_chain) read and immediately dereferences\nchain-\u003efilter_chain. A concurrent tcf_action_set_ctrlact() (e.g. the gact\nreplace path) can clear a-\u003egoto_chain between the two reads, so the second\nread returns NULL and tcf_action_goto_chain_exec() dereferences NULL.\n\nFix the race by doing a single rcu_dereference_bh() read of a-\u003egoto_chain\nin tcf_action_exec(), checking it once for NULL, and passing the resulting\nchain pointer into tcf_action_goto_chain_exec(). This turns the split\ncheck/use into a single check/use on one value."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-26T14:36:52.344Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/91d55fd1fdb85c8371ca8793c788ea7d5192383a"
        },
        {
          "url": "https://git.kernel.org/stable/c/1ec48b6715c29b20105e3485206602cff6c51ae5"
        },
        {
          "url": "https://git.kernel.org/stable/c/abceabc4408fca6a9dd52611f5d197dec9390d63"
        },
        {
          "url": "https://git.kernel.org/stable/c/6b70886ebc428eed43a069c8944a931b5fb3f4e4"
        },
        {
          "url": "https://git.kernel.org/stable/c/f60b396ee174206fe08ebf997d16cd3801b77b22"
        }
      ],
      "title": "net/sched: act_api: fix TOCTOU NULL deref on a-\u003egoto_chain",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-74740",
    "datePublished": "2026-08-26T14:36:52.344Z",
    "dateReserved": "2026-08-15T05:44:03.930Z",
    "dateUpdated": "2026-08-26T14:36:52.344Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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