GHSA-G4PX-H95H-7MGM

Vulnerability from github – Published: 2026-10-23 12:31 – Updated: 2026-10-23 12:31
VLAI
Details

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").

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{
  "affected": [],
  "aliases": [
    "CVE-2026-98888"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-10-23T12:18:22Z",
    "severity": null
  },
  "details": "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\").",
  "id": "GHSA-g4px-h95h-7mgm",
  "modified": "2026-10-23T12:31:37Z",
  "published": "2026-10-23T12:31:36Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-98888"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/1f342b3e44c3035a837b53b217d816f7511c0d0a"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/23f851ac0078a908bf3422d6467ebc1db5828c46"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/68774caca799e9695db56d426c69acebd041c2ed"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/a21bf9cb893126e8d9730995708d0be5eb167652"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/bb0fe9121aa0824211aafa33c7d0151fd25ddb75"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/c8e84e292ed4cfc199824146da71bb4397b02a1f"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f96a0606de6bcc8d937b80e6470fd7a174c17e26"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}



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