arm64: kprobes: Allow reentering kprobes while single-stepping

{
  "id": "fc00746b35eb41cdfb04f3e1f80ee87a8f532dd664f081480db17ee3fad82b07",
  "url": "https://www.cve.org/CVERecord?id=CVE-2026-98888",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "arm64: kprobes: Allow reentering kprobes while single-stepping",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: arm64: kprobes: Allow reentering kprobes while single-stepping A kprobe can be hit while another kprobe is in KPROBE_HIT_SS state. This can happen when tracing or perf code runs from the debug exception path while the first kprobe is preparing or executing its out-of-line single-step instruction. Currently arm64 treats a kprobe hit in KPROBE_HIT_SS as unrecoverable, the same as a hit in KPROBE_REENTER. This is too strict. A hit in KPROBE_HIT_SS is still a one-level reentry and can be handled by saving the current kprobe state and setting up single-step for the new probe, just like reentry from KPROBE_HIT_ACTIVE or KPROBE_HIT_SSDONE. The truly unrecoverable case is hitting another kprobe while already in KPROBE_REENTER, because the reentry save area has already been consumed. Move KPROBE_HIT_SS to the recoverable reentry cases and leave KPROBE_REENTER as the unrecoverable nested reentry case. This change also requires saving saved_irqflag in struct prev_kprobe. When a nested kprobe calls kprobes_save_local_irqflag(), it overwrites kcb->saved_irqflag with the currently masked DAIF value, losing the outer kprobe's original DAIF state. Without this fix, when the outer kprobe's single-step finishes, kprobes_restore_local_irqflag() applies the wrong DAIF mask and leaves interrupts permanently disabled. Extend struct prev_kprobe with a saved_irqflag field and save/restore it alongside kp and status. This ensures the",
    "evidence": "cve:CVE-2026-98888",
    "products": [
      {
        "name": {
          "value": "Linux",
          "evidence": "/containers/cna/affected/0/product"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": []
      },
      {
        "name": {
          "value": "Linux",
          "evidence": "/containers/cna/affected/1/product"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2026-98888",
      "aliases": [
        "CVE-2026-98888"
      ],
      "metrics": [],
      "affected": [
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "2dd0e8d2d2a157dbc83295a78336c2217110f2f8",
              "lessThan": "bb0fe9121aa0824211aafa33c7d0151fd25ddb75",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "2dd0e8d2d2a157dbc83295a78336c2217110f2f8",
              "lessThan": "f96a0606de6bcc8d937b80e6470fd7a174c17e26",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "2dd0e8d2d2a157dbc83295a78336c2217110f2f8",
              "lessThan": "1f342b3e44c3035a837b53b217d816f7511c0d0a",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "2dd0e8d2d2a157dbc83295a78336c2217110f2f8",
              "lessThan": "c8e84e292ed4cfc199824146da71bb4397b02a1f",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "2dd0e8d2d2a157dbc83295a78336c2217110f2f8",
              "lessThan": "68774caca799e9695db56d426c69acebd041c2ed",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "2dd0e8d2d2a157dbc83295a78336c2217110f2f8",
              "lessThan": "a21bf9cb893126e8d9730995708d0be5eb167652",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "2dd0e8d2d2a157dbc83295a78336c2217110f2f8",
              "lessThan": "23f851ac0078a908bf3422d6467ebc1db5828c46",
              "versionType": "git"
            }
          ],
          "programFiles": [
            "arch/arm64/include/asm/kprobes.h",
            "arch/arm64/kernel/probes/kprobes.c"
          ],
          "defaultStatus": "unaffected"
        },
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "4.8"
            },
            {
              "status": "unaffected",
              "version": "0",
              "lessThan": "4.8",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "5.10.271",
              "versionType": "semver",
              "lessThanOrEqual": "5.10.*"
            },
            {
              "status": "unaffected",
              "version": "5.15.222",
              "versionType": "semver",
              "lessThanOrEqual": "5.15.*"
            },
            {
              "status": "unaffected",
              "version": "6.1.189",
              "versionType": "semver",
              "lessThanOrEqual": "6.1.*"
            },
            {
              "status": "unaffected",
              "version": "6.6.158",
              "versionType": "semver",
              "lessThanOrEqual": "6.6.*"
            },
            {
              "status": "unaffected",
              "version": "6.12.111",
              "versionType": "semver",
              "lessThanOrEqual": "6.12.*"
            },
            {
              "status": "unaffected",
              "version": "6.18.53",
              "versionType": "semver",
              "lessThanOrEqual": "6.18.*"
            },
            {
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ],
          "programFiles": [
            "arch/arm64/include/asm/kprobes.h",
            "arch/arm64/kernel/probes/kprobes.c"
          ],
          "defaultStatus": "affected"
        }
      ],
      "modified": "2026-10-26T06:56:13.106Z",
      "provider": "cve",
      "references": [
        "https://git.kernel.org/stable/c/bb0fe9121aa0824211aafa33c7d0151fd25ddb75",
        "https://git.kernel.org/stable/c/f96a0606de6bcc8d937b80e6470fd7a174c17e26",
        "https://git.kernel.org/stable/c/1f342b3e44c3035a837b53b217d816f7511c0d0a",
        "https://git.kernel.org/stable/c/c8e84e292ed4cfc199824146da71bb4397b02a1f",
        "https://git.kernel.org/stable/c/68774caca799e9695db56d426c69acebd041c2ed",
        "https://git.kernel.org/stable/c/a21bf9cb893126e8d9730995708d0be5eb167652",
        "https://git.kernel.org/stable/c/23f851ac0078a908bf3422d6467ebc1db5828c46"
      ],
      "provider_metadata": {
        "cna": {
          "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
          "shortName": "Linux",
          "dateUpdated": "2026-10-26T06:56:13.106Z"
        }
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-98888",
        "evidence": "/cveMetadata/cveId"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-cve",
  "document_id": 263346,
  "published_at": "2026-10-23T11:37:46.984+00:00"
}