{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2025-38170", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2025-04-16T04:51:23.991Z", "datePublished": "2025-07-03T08:36:09.012Z", "dateUpdated": "2026-05-11T21:22:36.924Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-05-11T21:22:36.924Z" }, "descriptions": [ { "lang": "en", "value": "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": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "arch/arm64/kernel/fpsimd.c" ], "versions": [ { "version": "8bd7f91c03d886f41d35f6108078d20be5a4a1bd", "lessThan": "de89368de3894a8db27caeb8fd902ba1c49f696a", "status": "affected", "versionType": "git" }, { "version": "8bd7f91c03d886f41d35f6108078d20be5a4a1bd", "lessThan": "43be952e885476dafb74aa832c0847b2f4f650c6", "status": "affected", "versionType": "git" }, { "version": "8bd7f91c03d886f41d35f6108078d20be5a4a1bd", "lessThan": "6103f9ba51a59afb5a0f32299c837377c5a5a693", "status": "affected", "versionType": "git" }, { "version": "8bd7f91c03d886f41d35f6108078d20be5a4a1bd", "lessThan": "c4a4786d93e99517d6f10ed56b9ffba4ce88d3b3", "status": "affected", "versionType": "git" }, { "version": "8bd7f91c03d886f41d35f6108078d20be5a4a1bd", "lessThan": "d3eaab3c70905c5467e5c4ea403053d67505adeb", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "arch/arm64/kernel/fpsimd.c" ], "versions": [ { "version": "5.19", "status": "affected" }, { "version": "0", "lessThan": "5.19", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.142", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.94", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.34", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.15.3", "lessThanOrEqual": "6.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.16", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.19", "versionEndExcluding": "6.1.142" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.19", "versionEndExcluding": "6.6.94" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.19", "versionEndExcluding": "6.12.34" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.19", "versionEndExcluding": "6.15.3" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.19", "versionEndExcluding": "6.16" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/de89368de3894a8db27caeb8fd902ba1c49f696a" }, { "url": "https://git.kernel.org/stable/c/43be952e885476dafb74aa832c0847b2f4f650c6" }, { "url": "https://git.kernel.org/stable/c/6103f9ba51a59afb5a0f32299c837377c5a5a693" }, { "url": "https://git.kernel.org/stable/c/c4a4786d93e99517d6f10ed56b9ffba4ce88d3b3" }, { "url": "https://git.kernel.org/stable/c/d3eaab3c70905c5467e5c4ea403053d67505adeb" } ], "title": "arm64/fpsimd: Discard stale CPU state when handling SME traps", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "title": "CVE Program Container", "references": [ { "url": "https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html" } ], "providerMetadata": { "orgId": "af854a3a-2127-422b-91ae-364da2661108", "shortName": "CVE", "dateUpdated": "2025-11-03T17:34:57.733Z" } } ] } }