Answer in brief
CVE-2025-38170 records a Medium severity (CVSS 5.5) vulnerability in arm64/fpsimd: Discard stale CPU state when handling SME traps. The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 5.5. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
| Product | Affected versions | Fixed versions |
|---|---|---|
| cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:* | Not reported | Not reported |
| cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | Not reported | Not reported |
| Package | Affected range | Fixed version |
|---|---|---|
| Linux/Linuxgeneric | >=8bd7f91c03d886f41d35f6108078d20be5a4a1bd <de89368de3894a8db27caeb8fd902ba1c49f696a || >=8bd7f91c03d886f41d35f6108078d20be5a4a1bd <43be952e885476dafb74aa832c0847b2f4f650c6 || >=8bd7f91c03d886f41d35f6108078d20be5a4a1bd <6103f9ba51a59afb5a0f32299c837377c5a5a693 || >=8bd7f91c03d886f41d35f6108078d20be5a4a1bd <c4a4786d93e99517d6f10ed56b9ffba4ce88d3b3 || >=8bd7f91c03d886f41d35f6108078d20be5a4a1bd <d3eaab3c70905c5467e5c4ea403053d67505adeb | de89368de3894a8db27caeb8fd902ba1c49f696a, 43be952e885476dafb74aa832c0847b2f4f650c6, 6103f9ba51a59afb5a0f32299c837377c5a5a693, c4a4786d93e99517d6f10ed56b9ffba4ce88d3b3, d3eaab3c70905c5467e5c4ea403053d67505adeb |
| Linux/Linuxgeneric | 5.19 | Not reported |
Published upstream
Jul 3, 2025
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Nov 5, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Nov 5, 2026
In the Linux kernel, the following vulnerability has been resolved: arm64/fpsimd: Discard stale CPU state when handling SME traps The logic for handling SME traps manipulates saved FPSIMD/SVE/SME state incorrectly, and a race with preemption can result in a task having TIF_SME set and TIF_FOREIGN_FPSTATE clear even though the live CPU state is stale (e.g. with SME traps enabled). This can result in warnings from do_sme_acc() where SME traps are not expected while TIF_SME is set: | /* With TIF_SME userspace shouldn't generate any traps */ | if (test_and_set_thread_flag(TIF_SME)) | WARN_ON(1); This is very similar to the SVE issue we fixed in commit: 751ecf6afd6568ad ("arm64/sve: Discard stale CPU state when handling SVE traps") The race can occur when the SME trap handler is preempted before and after manipulating the saved FPSIMD/SVE/SME state, starting and ending on the same CPU, e.g. | void do_sme_acc(unsigned long esr, struct pt_regs *regs) | { | // Trap on CPU 0 with TIF_SME clear, SME traps enabled | // task->fpsimd_cpu is 0. | // per_cpu_ptr(&fpsimd_last_state, 0) is task. | | ... | | // Preempted; migrated from CPU 0 to CPU 1. | // TIF_FOREIGN_FPSTATE is set. | | get_cpu_fpsimd_context(); | | /* With TIF_SME userspace shouldn't generate any traps */ | if (test_and_set_thread_flag(TIF_SME)) | WARN_ON(1); | | if (!test_thread_flag(TIF_FOREIGN_FPSTATE)) { | unsigned long vq_minus_one = | sve_vq_from_vl(task_get_sme_vl(current)) - 1; | sme_set_vq(vq_minus_one); | | fpsimd_bind_task_to_cpu(); | } | | put_cpu_fpsimd_context(); | | // Preempted; migrated from CPU 1 to CPU 0. | // task->fpsimd_cpu is still 0 | // If per_cpu_ptr(&fpsimd_last_state, 0) is still task then: | // - Stale HW state is reused (with SME traps enabled) | // - TIF_FOREIGN_FPSTATE is cleared | // - A return to userspace skips HW state restore | } Fix the case where the state is not live and TIF_FOREIGN_FPSTATE is set by calling fpsimd_flush_task_state() to detach from the saved CPU state. This ensures that a subsequent context switch will not reuse the stale CPU state, and will instead set TIF_FOREIGN_FPSTATE, forcing the new state to be reloaded from memory prior to a return to userspace. Note: this was originallly posted as [1]. [ Rutland: rewrite commit message ]
Quoted source text, attributed separately from HOL analysis.