CVE-2026-90211 (GCVE-0-2026-90211)

Vulnerability from cvelistv5 – Published: 2026-09-17 16:07 – Updated: 2026-10-19 08:59
VLAI
Title
bpf, s390: Clear fetch destination on faulting arena atomic
Summary
In the Linux kernel, the following vulnerability has been resolved: bpf, s390: Clear fetch destination on faulting arena atomic Same missing register clear as on riscv64. A RMW atomic on an arena pointer is converted to BPF_PROBE_ATOMIC and gets an exception table entry, but bpf_jit_probe_atomic_pre() only fills in the arena base and the probe offset, leaving probe->reg at the -1 that bpf_jit_probe_init() set, which bpf_jit_probe_post() writes into the entry and ex_handler_bpf() then reads back as "there is nothing to clear". That is right for a plain BPF_{ADD,AND,OR,XOR}, which only writes memory, but an RMW carrying BPF_FETCH also reads the old value into a register: src_reg for BPF_{ADD,AND,OR,XOR} | BPF_FETCH and BPF_XCHG, and r0 for BPF_CMPXCHG. So on a fault over an unmapped arena page the program resumes at the landing pad with whatever that register held before the atomic instead of the 0 that every other BPF_PROBE_* access delivers. Fill probe->reg in from bpf_atomic_load_reg(). Unlike x86-64 and arm64, s390x does not report arena violations from its exception handler, so there is no access direction to correct here, only the missing register clear.
Severity
No CVSS data available.
Assigner
Linux CNA under the mitre root
CNA scorecard D 53/100 over 6846 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 2f9469484a3b52c66b799de73bd1ca75617bc8d5 , < 44b702fceb4cf3a4ddbfb496f487b034814bf1a3 (git)
Affected: 2f9469484a3b52c66b799de73bd1ca75617bc8d5 , < cc3e12330599f097f0e1f792435686ddc276f26d (git)
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Linux Linux Affected: 6.11
Unaffected: 0 , < 6.11 (semver)
Unaffected: 7.2.6 , ≤ 7.2.* (semver)
Unaffected: 7.3 , ≤ * (original_commit_for_fix)
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "arch/s390/net/bpf_jit_comp.c"
          ],
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          "versions": [
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      "cpeApplicability": [
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          "nodes": [
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                  "vulnerable": true
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          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf, s390: Clear fetch destination on faulting arena atomic\n\nSame missing register clear as on riscv64. A RMW atomic on an arena pointer\nis converted to BPF_PROBE_ATOMIC and gets an exception table entry, but\nbpf_jit_probe_atomic_pre() only fills in the arena base and the probe\noffset, leaving probe-\u003ereg at the -1 that bpf_jit_probe_init() set, which\nbpf_jit_probe_post() writes into the entry and ex_handler_bpf() then reads\nback as \"there is nothing to clear\".\n\nThat is right for a plain BPF_{ADD,AND,OR,XOR}, which only writes memory,\nbut an RMW carrying BPF_FETCH also reads the old value into a register:\nsrc_reg for BPF_{ADD,AND,OR,XOR} | BPF_FETCH and BPF_XCHG, and r0 for\nBPF_CMPXCHG. So on a fault over an unmapped arena page the program resumes\nat the landing pad with whatever that register held before the atomic\ninstead of the 0 that every other BPF_PROBE_* access delivers.\n\nFill probe-\u003ereg in from bpf_atomic_load_reg(). Unlike x86-64 and arm64,\ns390x does not report arena violations from its exception handler, so there\nis no access direction to correct here, only the missing register clear."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-19T08:59:47.377Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/44b702fceb4cf3a4ddbfb496f487b034814bf1a3"
        },
        {
          "url": "https://git.kernel.org/stable/c/cc3e12330599f097f0e1f792435686ddc276f26d"
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      "title": "bpf, s390: Clear fetch destination on faulting arena atomic",
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  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-90211",
    "datePublished": "2026-09-17T16:07:25.454Z",
    "dateReserved": "2026-09-11T19:38:34.793Z",
    "dateUpdated": "2026-10-19T08:59:47.377Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
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      "date": "2026-11-03",
      "epss": "0.00198",
      "percentile": "0.0961"
    },
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      "cve": "CVE-2026-90211",
      "id": "msrc_CVE-2026-90211",
      "initial_release_date": "2026-10-20T22:22:05.000Z",
      "product_status:under_investigation": "1",
      "source": "Microsoft CSAF VEX",
      "status": "final",
      "title": "bpf, s390: Clear fetch destination on faulting arena atomic",
      "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-90211.json",
      "version": "2"
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    "nvd": {
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                "product": "Linux",
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                ],
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        "cveTags": [],
        "descriptions": [
          {
            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf, s390: Clear fetch destination on faulting arena atomic\n\nSame missing register clear as on riscv64. A RMW atomic on an arena pointer\nis converted to BPF_PROBE_ATOMIC and gets an exception table entry, but\nbpf_jit_probe_atomic_pre() only fills in the arena base and the probe\noffset, leaving probe-\u003ereg at the -1 that bpf_jit_probe_init() set, which\nbpf_jit_probe_post() writes into the entry and ex_handler_bpf() then reads\nback as \"there is nothing to clear\".\n\nThat is right for a plain BPF_{ADD,AND,OR,XOR}, which only writes memory,\nbut an RMW carrying BPF_FETCH also reads the old value into a register:\nsrc_reg for BPF_{ADD,AND,OR,XOR} | BPF_FETCH and BPF_XCHG, and r0 for\nBPF_CMPXCHG. So on a fault over an unmapped arena page the program resumes\nat the landing pad with whatever that register held before the atomic\ninstead of the 0 that every other BPF_PROBE_* access delivers.\n\nFill probe-\u003ereg in from bpf_atomic_load_reg(). Unlike x86-64 and arm64,\ns390x does not report arena violations from its exception handler, so there\nis no access direction to correct here, only the missing register clear."
          }
        ],
        "id": "CVE-2026-90211",
        "lastModified": "2026-10-19T09:19:11.277",
        "metrics": {},
        "published": "2026-09-17T17:17:16.330",
        "references": [
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/44b702fceb4cf3a4ddbfb496f487b034814bf1a3"
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            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/cc3e12330599f097f0e1f792435686ddc276f26d"
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        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Received"
      }
    },
    "redhat_vex": {
      "aggregate_severity": "Low",
      "current_release_date": "2026-10-13T16:58:07+00:00",
      "cve": "CVE-2026-90211",
      "id": "CVE-2026-90211",
      "initial_release_date": "2026-09-17T00:00:00+00:00",
      "product_status:known_affected": "184",
      "product_status:known_not_affected": "93",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: bpf, s390: Clear fetch destination on faulting arena atomic",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-90211.json",
      "version": "3"
    },
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      "aggregate_severity": "low",
      "current_release_date": "2026-10-20T00:43:10Z",
      "cve": "CVE-2026-90211",
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      "product_status:recommended": "4",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-90211",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/2026/cve-2026-90211.json",
      "version": "6"
    }
  }
}



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