fkie_cve-2025-68171
Vulnerability from fkie_nvd
Published
2025-12-16 14:15
Modified
2025-12-18 15:08
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: x86/fpu: Ensure XFD state on signal delivery Sean reported [1] the following splat when running KVM tests: WARNING: CPU: 232 PID: 15391 at xfd_validate_state+0x65/0x70 Call Trace: <TASK> fpu__clear_user_states+0x9c/0x100 arch_do_signal_or_restart+0x142/0x210 exit_to_user_mode_loop+0x55/0x100 do_syscall_64+0x205/0x2c0 entry_SYSCALL_64_after_hwframe+0x4b/0x53 Chao further identified [2] a reproducible scenario involving signal delivery: a non-AMX task is preempted by an AMX-enabled task which modifies the XFD MSR. When the non-AMX task resumes and reloads XSTATE with init values, a warning is triggered due to a mismatch between fpstate::xfd and the CPU's current XFD state. fpu__clear_user_states() does not currently re-synchronize the XFD state after such preemption. Invoke xfd_update_state() which detects and corrects the mismatch if there is a dynamic feature. This also benefits the sigreturn path, as fpu__restore_sig() may call fpu__clear_user_states() when the sigframe is inaccessible. [ dhansen: minor changelog munging ]
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/1811c610653c0cd21cc9add14595b7cffaeca511
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/388eff894d6bc5f921e9bfff0e4b0ab2684a96e9
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/3f735419c4b43cde42e6d408db39137b82474e31
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/5b2619b488f1d08b960c43c6468dd0759e8b3035
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/eefbfb722042fc9210d2e0ac2b063fd1abf51895
Impacted products
Vendor Product Version


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{
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nx86/fpu: Ensure XFD state on signal delivery\n\nSean reported [1] the following splat when running KVM tests:\n\n   WARNING: CPU: 232 PID: 15391 at xfd_validate_state+0x65/0x70\n   Call Trace:\n    \u003cTASK\u003e\n    fpu__clear_user_states+0x9c/0x100\n    arch_do_signal_or_restart+0x142/0x210\n    exit_to_user_mode_loop+0x55/0x100\n    do_syscall_64+0x205/0x2c0\n    entry_SYSCALL_64_after_hwframe+0x4b/0x53\n\nChao further identified [2] a reproducible scenario involving signal\ndelivery: a non-AMX task is preempted by an AMX-enabled task which\nmodifies the XFD MSR.\n\nWhen the non-AMX task resumes and reloads XSTATE with init values,\na warning is triggered due to a mismatch between fpstate::xfd and the\nCPU\u0027s current XFD state. fpu__clear_user_states() does not currently\nre-synchronize the XFD state after such preemption.\n\nInvoke xfd_update_state() which detects and corrects the mismatch if\nthere is a dynamic feature.\n\nThis also benefits the sigreturn path, as fpu__restore_sig() may call\nfpu__clear_user_states() when the sigframe is inaccessible.\n\n[ dhansen: minor changelog munging ]"
    }
  ],
  "id": "CVE-2025-68171",
  "lastModified": "2025-12-18T15:08:25.907",
  "metrics": {},
  "published": "2025-12-16T14:15:48.980",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/1811c610653c0cd21cc9add14595b7cffaeca511"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/388eff894d6bc5f921e9bfff0e4b0ab2684a96e9"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/3f735419c4b43cde42e6d408db39137b82474e31"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/5b2619b488f1d08b960c43c6468dd0759e8b3035"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/eefbfb722042fc9210d2e0ac2b063fd1abf51895"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Awaiting Analysis"
}


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