mptcp: fix 'scheduling while atomic' in mptcp_pm_nl_append_new_local_addr

{
  "id": "5c272ee4622d8aebc2788c552f8396a91d44a623da9fa281e50138815fef98d3",
  "url": "https://osv.dev/vulnerability/CVE-2025-21938",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "mptcp: fix 'scheduling while atomic' in mptcp_pm_nl_append_new_local_addr",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: mptcp: fix 'scheduling while atomic' in mptcp_pm_nl_append_new_local_addr If multiple connection requests attempt to create an implicit mptcp endpoint in parallel, more than one caller may end up in mptcp_pm_nl_append_new_local_addr because none found the address in local_addr_list during their call to mptcp_pm_nl_get_local_id. In this case, the concurrent new_local_addr calls may delete the address entry created by the previous caller. These deletes use synchronize_rcu, but this is not permitted in some of the contexts where this function may be called. During packet recv, the caller may be in a rcu read critical section and have preemption disabled. An example stack: BUG: scheduling while atomic: swapper/2/0/0x00000302 Call Trace: dump_stack_lvl (lib/dump_stack.c:117 (discriminator 1)) dump_stack (lib/dump_stack.c:124) __schedule_bug (kernel/sched/core.c:5943) schedule_debug.constprop.0 (arch/x86/include/asm/preempt.h:33 kernel/sched/core.c:5970) __schedule (arch/x86/include/asm/jump_label.h:27 include/linux/jump_label.h:207 kernel/sched/features.h:29 kernel/sched/core.c:6621) schedule (arch/x86/include/asm/preempt.h:84 kernel/sched/core.c:6804 kernel/sched/core.c:6818) schedule_timeout (kernel/time/timer.c:2160) wait_for_completion (kernel/sched/completion.c:96 kernel/sched/completion.c:116 kernel/sched/completion.c:127 kernel/sched/completion.c:148) __wait_rcu_gp (include/linux/rcupdate.h:311 kernel/rcu/u",
    "evidence": "osv:CVE-2025-21938",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.1.131",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.6.83",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.12.19",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.13.7",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "high",
    "structured": {
      "id": "CVE-2025-21938",
      "aliases": [
        "CVE-2025-21938"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
        }
      ],
      "affected": [
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                },
                {
                  "fixed": "f3fcdb2de9fdbed9d8c6a8eb2c5fbd7d6f54a4d8"
                },
                {
                  "fixed": "4b228dae3d2cc6d9dce167449cd8fa9f028e9376"
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                {
                  "fixed": "125ccafe6dd062901b5a0c31ee9038740fc8859e"
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            "ecosystem": "Linux"
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            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-21938.json"
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      ],
      "modified": "2026-10-28T02:30:53.489423497Z",
      "provider": "osv",
      "references": [
        "https://cert-portal.siemens.com/productcert/html/ssa-019113.html",
        "https://cert-portal.siemens.com/productcert/html/ssa-457936.html",
        "https://git.kernel.org/stable/c/022bfe24aad8937705704ff2e414b100cf0f2e1a",
        "https://git.kernel.org/stable/c/125ccafe6dd062901b5a0c31ee9038740fc8859e",
        "https://git.kernel.org/stable/c/4b228dae3d2cc6d9dce167449cd8fa9f028e9376",
        "https://git.kernel.org/stable/c/f1404f368c40fc6a068dad72e4ee0824ee6a78ee",
        "https://git.kernel.org/stable/c/f3fcdb2de9fdbed9d8c6a8eb2c5fbd7d6f54a4d8",
        "https://lists.debian.org/debian-lts-announce/2025/05/msg00045.html",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/21xxx/CVE-2025-21938.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2025-21938",
        "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/2025/21xxx/CVE-2025-21938.json"
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    "related_cves": [
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        "value": "CVE-2025-21938",
        "evidence": "/id"
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    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 522008,
  "published_at": "2025-04-01T15:41:04.886+00:00"
}