{ "schemaVersion": 1, "attribution": [ { "source": "CISA Known Exploited Vulnerabilities", "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog", "licence": "US government work" }, { "source": "GitHub Advisory Database", "url": "https://github.com/advisories", "licence": "CC BY 4.0" }, { "source": "Have I Been Pwned", "url": "https://haveibeenpwned.com/", "licence": "CC BY 4.0" }, { "source": "CVE Program (CVE records)", "url": "https://www.cve.org/Legal/TermsOfUse", "licence": "CVE Terms of Use", "notice": "Copyright © 1999-2026, The MITRE Corporation. CVE is a trademark and the CVE logo is a registered trademark of The MITRE Corporation.", "terms": "CVE Usage: MITRE hereby grants you a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable copyright license to reproduce, prepare derivative works of, publicly display, publicly perform, sublicense, and distribute Common Vulnerabilities and Exposures (CVE™). Any copy you make for such purposes is authorized provided that you reproduce MITRE's copyright designation and this license in any such copy." }, { "source": "FIRST EPSS", "url": "https://www.first.org/epss/", "licence": "free to use; FIRST requests attribution" } ], "record": { "id": "CVE-2025-38170", "sourceURL": "https://www.cve.org/CVERecord?id=CVE-2025-38170", "idYear": 2025, "status": "PUBLISHED", "publishedAt": "2025-07-03T08:36:09.012Z", "updatedAt": "2026-05-11T21:22:36.924Z", "importedAt": "2026-10-24T01:57:34.152Z", "snapshot": { "id": "cve_2026-10-24_midnight_baseline", "at": "2026-10-24T00:00:00.000Z", "source": "https://github.com/CVEProject/cvelistV5/releases/tag/cve_2026-10-24_0100Z" }, "facts": { "title": "arm64/fpsimd: Discard stale CPU state when handling SME traps", "summary": "In the Linux kernel, the following vulnerability has been resolved:\n\narm64/fpsimd: Discard stale CPU state when handling SME traps\n\nThe logic for handling SME traps manipulates saved FPSIMD/SVE/SME state\nincorrectly, and a race with preemption can result in a task having\nTIF_SME set and TIF_FOREIGN_FPSTATE clear even though the live CPU state\nis stale (e.g. with SME traps enabled). This can result in warnings from\ndo_sme_acc() where SME traps are not expected while TIF_SME is set:\n\n| /* With TIF_SME userspace shouldn't generate any traps */\n| if (test_and_set_thread_flag(TIF_SME))\n| WARN_ON(1);\n\nThis is very similar to the SVE issue we fixed in commit:\n\n 751ecf6afd6568ad (\"arm64/sve: Discard stale CPU state when handling SVE traps\")\n\nThe race can occur when the SME trap handler is preempted before and\nafter manipulating the saved FPSIMD/SVE/SME state, starting and ending on\nthe same CPU, e.g.\n\n| void do_sme_acc(unsigned long esr, struct pt_regs *regs)\n| {\n| // Trap on CPU 0 with TIF_SME clear, SME traps enabled\n| // task->fpsimd_cpu is 0.\n| // per_cpu_ptr(&fpsimd_last_state, 0) is task.\n|\n| ...\n|\n| // Preempted; migrated from CPU 0 to CPU 1.\n| // TIF_FOREIGN_FPSTATE is set.\n|\n| get_cpu_fpsimd_context();\n|\n| /* With TIF_SME userspace shouldn't generate any traps */\n| if (test_and_set_thread_flag(TIF_SME))\n| WARN_ON(1);\n|\n| if (!test_thread_flag(TIF_FOREIGN_FPSTATE)) {\n| unsigned long vq_minus_one =\n| sve_vq_from_vl(task_get_sme_vl(current)) - 1;\n| sme_set_vq(vq_minus_one);\n|\n| fpsimd_bind_task_to_cpu();\n| }\n|\n| put_cpu_fpsimd_context();\n|\n| // Preempted; migrated from CPU 1 to CPU 0.\n| // task->fpsimd_cpu is still 0\n| // If per_cpu_ptr(&fpsimd_last_state, 0) is still task then:\n| // - Stale HW state is reused (with SME traps enabled)\n| // - TIF_FOREIGN_FPSTATE is cleared\n| // - A return to userspace skips HW state restore\n| }\n\nFix the case where the state is not live and TIF_FOREIGN_FPSTATE is set\nby calling fpsimd_flush_task_state() to detach from the saved CPU\nstate. This ensures that a subsequent context switch will not reuse the\nstale CPU state, and will instead set TIF_FOREIGN_FPSTATE, forcing the\nnew state to be reloaded from memory prior to a return to userspace.\n\nNote: this was originallly posted as [1].\n\n[ Rutland: rewrite commit message ]", "affected": [ { "vendor": "Linux", "product": "Linux", "defaultStatus": "unaffected", "versions": [ { "version": "8bd7f91c03d886f41d35f6108078d20be5a4a1bd", "status": "affected", "versionType": "git", "lessThan": "de89368de3894a8db27caeb8fd902ba1c49f696a" }, { "version": "8bd7f91c03d886f41d35f6108078d20be5a4a1bd", "status": "affected", "versionType": "git", "lessThan": "43be952e885476dafb74aa832c0847b2f4f650c6" }, { "version": "8bd7f91c03d886f41d35f6108078d20be5a4a1bd", "status": "affected", "versionType": "git", "lessThan": "6103f9ba51a59afb5a0f32299c837377c5a5a693" }, { "version": "8bd7f91c03d886f41d35f6108078d20be5a4a1bd", "status": "affected", "versionType": "git", "lessThan": "c4a4786d93e99517d6f10ed56b9ffba4ce88d3b3" }, { "version": "8bd7f91c03d886f41d35f6108078d20be5a4a1bd", "status": "affected", "versionType": "git", "lessThan": "d3eaab3c70905c5467e5c4ea403053d67505adeb" } ] }, { "vendor": "Linux", "product": "Linux", "defaultStatus": "affected", "versions": [ { "version": "5.19", "status": "affected" }, { "version": "0", "status": "unaffected", "versionType": "semver", "lessThan": "5.19" }, { "version": "6.1.142", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.1.*" }, { "version": "6.6.94", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.6.*" }, { "version": "6.12.34", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.12.*" }, { "version": "6.15.3", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.15.*" }, { "version": "6.16", "status": "unaffected", "versionType": "original_commit_for_fix", "lessThanOrEqual": "*" } ] } ] } } }