ghsa-4ggp-pgr3-73m2
Vulnerability from github
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: 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 ]
{
"affected": [],
"aliases": [
"CVE-2025-68171"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-12-16T14:15:48Z",
"severity": null
},
"details": "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": "GHSA-4ggp-pgr3-73m2",
"modified": "2025-12-16T15:30:44Z",
"published": "2025-12-16T15:30:44Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-68171"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/1811c610653c0cd21cc9add14595b7cffaeca511"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/388eff894d6bc5f921e9bfff0e4b0ab2684a96e9"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/3f735419c4b43cde42e6d408db39137b82474e31"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/5b2619b488f1d08b960c43c6468dd0759e8b3035"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/eefbfb722042fc9210d2e0ac2b063fd1abf51895"
}
],
"schema_version": "1.4.0",
"severity": []
}
Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.