In the Linux kernel, the following vulnerability has been resolved:
arm64/fpsimd: Avoid clobbering kernel FPSIMD state with SMSTOP
On system with SME, a thread's kernel FPSIMD state may be erroneously
clobbered during a context switch immediately after that state is
restored. Systems without SME are unaffected.
If the CPU happens to be in streaming SVE mode before a context switch
to a thread with kernel FPSIMD state, fpsimd_thread_switch() will
restore the kernel FPSIMD state using fpsimd_load_kernel_state() while
the CPU is still in streaming SVE mode. When fpsimd_thread_switch()
subsequently calls fpsimd_flush_cpu_state(), this will execute an
SMSTOP, causing an exit from streaming SVE mode. The exit from
streaming SVE mode will cause the hardware to reset a number of
FPSIMD/SVE/SME registers, clobbering the FPSIMD state.
Fix this by calling fpsimd_flush_cpu_state() before restoring the kernel
FPSIMD state.
Metrics
Affected Vendors & Products
References
History
Thu, 03 Jul 2025 09:00:00 +0000
Type | Values Removed | Values Added |
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Description | In the Linux kernel, the following vulnerability has been resolved: arm64/fpsimd: Avoid clobbering kernel FPSIMD state with SMSTOP On system with SME, a thread's kernel FPSIMD state may be erroneously clobbered during a context switch immediately after that state is restored. Systems without SME are unaffected. If the CPU happens to be in streaming SVE mode before a context switch to a thread with kernel FPSIMD state, fpsimd_thread_switch() will restore the kernel FPSIMD state using fpsimd_load_kernel_state() while the CPU is still in streaming SVE mode. When fpsimd_thread_switch() subsequently calls fpsimd_flush_cpu_state(), this will execute an SMSTOP, causing an exit from streaming SVE mode. The exit from streaming SVE mode will cause the hardware to reset a number of FPSIMD/SVE/SME registers, clobbering the FPSIMD state. Fix this by calling fpsimd_flush_cpu_state() before restoring the kernel FPSIMD state. | |
Title | arm64/fpsimd: Avoid clobbering kernel FPSIMD state with SMSTOP | |
References |
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Status: PUBLISHED
Assigner: Linux
Published: 2025-07-03T08:36:08.393Z
Updated: 2025-07-03T08:36:08.393Z
Reserved: 2025-04-16T04:51:23.991Z
Link: CVE-2025-38169

No data.

Status : Awaiting Analysis
Published: 2025-07-03T09:15:32.517
Modified: 2025-07-03T15:13:53.147
Link: CVE-2025-38169

No data.