CVE-2025-38169

EPSS 0.05%
Veröffentlicht 03.07.2025 08:36:08
Zuletzt bearbeitet 20.11.2025 19:28:15
Quelle 416baaa9-dc9f-4396-8d5f-8c081f
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arm64/fpsimd: Avoid clobbering kernel FPSIMD state with SMSTOP

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.