CVE-2025-38169 Information

Jul 04, 2025 cve

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.

Reference

https://git.kernel.org/stable/c/01098d893fa8a6edb2b56e178b798e3e6b674f02 https://git.kernel.org/stable/c/55d52af498daea75aa03ba9b7e444c8ae495ac20 https://git.kernel.org/stable/c/a305821f597ec943849d3e53924adb88c61ed682

CNNVD-202507-253 (Published: 2025-07-03)

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