CVE-2026-98888 (GCVE-0-2026-98888)
Vulnerability from cvelistv5
Published
2026-10-23 11:37
Modified
2026-10-26 06:56
Severity ?
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 outer kprobe's original interrupt state is preserved across reentry. This mirrors the x86 fix in commit 6a5022a56ac3 ("kprobes/x86: Allow to handle reentered kprobe on single-stepping").
References
Impacted products
Vendor Product Version
Linux Linux Version: 2dd0e8d2d2a157dbc83295a78336c2217110f2f8
Version: 2dd0e8d2d2a157dbc83295a78336c2217110f2f8
Version: 2dd0e8d2d2a157dbc83295a78336c2217110f2f8
Version: 2dd0e8d2d2a157dbc83295a78336c2217110f2f8
Version: 2dd0e8d2d2a157dbc83295a78336c2217110f2f8
Version: 2dd0e8d2d2a157dbc83295a78336c2217110f2f8
Version: 2dd0e8d2d2a157dbc83295a78336c2217110f2f8
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{
  "containers": {
    "cna": {
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        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "arch/arm64/include/asm/kprobes.h",
            "arch/arm64/kernel/probes/kprobes.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
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          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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              "version": "0",
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              "version": "5.10.271",
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            },
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              "lessThanOrEqual": "5.15.*",
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              "version": "5.15.222",
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            },
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              "lessThanOrEqual": "6.1.*",
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              "version": "6.1.189",
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              "version": "6.12.111",
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              "lessThanOrEqual": "6.18.*",
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              "version": "6.18.53",
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            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
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              "cpeMatch": [
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              "negate": false,
              "operator": "OR"
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          ]
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      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\narm64: kprobes: Allow reentering kprobes while single-stepping\n\nA kprobe can be hit while another kprobe is in KPROBE_HIT_SS state. This\ncan happen when tracing or perf code runs from the debug exception path\nwhile the first kprobe is preparing or executing its out-of-line\nsingle-step instruction.\n\nCurrently arm64 treats a kprobe hit in KPROBE_HIT_SS as unrecoverable,\nthe same as a hit in KPROBE_REENTER. This is too strict. A hit in\nKPROBE_HIT_SS is still a one-level reentry and can be handled by saving\nthe current kprobe state and setting up single-step for the new probe,\njust like reentry from KPROBE_HIT_ACTIVE or KPROBE_HIT_SSDONE.\n\nThe truly unrecoverable case is hitting another kprobe while already in\nKPROBE_REENTER, because the reentry save area has already been consumed.\n\nMove KPROBE_HIT_SS to the recoverable reentry cases and leave\nKPROBE_REENTER as the unrecoverable nested reentry case.\n\nThis change also requires saving saved_irqflag in struct prev_kprobe.\nWhen a nested kprobe calls kprobes_save_local_irqflag(), it overwrites\nkcb-\u003esaved_irqflag with the currently masked DAIF value, losing the\nouter kprobe\u0027s original DAIF state. Without this fix, when the outer\nkprobe\u0027s single-step finishes, kprobes_restore_local_irqflag() applies\nthe wrong DAIF mask and leaves interrupts permanently disabled.\n\nExtend struct prev_kprobe with a saved_irqflag field and save/restore it\nalongside kp and status. This ensures the outer kprobe\u0027s original\ninterrupt state is preserved across reentry.\n\nThis mirrors the x86 fix in commit 6a5022a56ac3\n(\"kprobes/x86: Allow to handle reentered kprobe on single-stepping\")."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-26T06:56:13.106Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/bb0fe9121aa0824211aafa33c7d0151fd25ddb75"
        },
        {
          "url": "https://git.kernel.org/stable/c/f96a0606de6bcc8d937b80e6470fd7a174c17e26"
        },
        {
          "url": "https://git.kernel.org/stable/c/1f342b3e44c3035a837b53b217d816f7511c0d0a"
        },
        {
          "url": "https://git.kernel.org/stable/c/c8e84e292ed4cfc199824146da71bb4397b02a1f"
        },
        {
          "url": "https://git.kernel.org/stable/c/68774caca799e9695db56d426c69acebd041c2ed"
        },
        {
          "url": "https://git.kernel.org/stable/c/a21bf9cb893126e8d9730995708d0be5eb167652"
        },
        {
          "url": "https://git.kernel.org/stable/c/23f851ac0078a908bf3422d6467ebc1db5828c46"
        }
      ],
      "title": "arm64: kprobes: Allow reentering kprobes while single-stepping",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-98888",
    "datePublished": "2026-10-23T11:37:46.984Z",
    "dateReserved": "2026-09-25T10:25:14.378Z",
    "dateUpdated": "2026-10-26T06:56:13.106Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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