CVE-2026-23102 — arm64/fpsimd: signal: Fix restoration of SVE context

Affected: Linux

In the Linux kernel, the following vulnerability has been resolved:

arm64/fpsimd: signal: Fix restoration of SVE context

When SME is supported, Restoring SVE signal context can go wrong in a few ways, including placing the task into an invalid state where the kernel may read from out-of-bounds memory (and may potentially take a fatal fault) and/or may kill the task with a SIGKILL.

(1) Restoring a context with SVE_SIG_FLAG_SM set can place the task into an invalid state where SVCR.SM is set (and sve_state is non-NULL) but TIF_SME is clear, consequently resuting in out-of-bounds memory reads and/or killing the task with SIGKILL.

This can only occur in unusual (but legitimate) cases where the SVE signal context has either been modified by userspace or was saved in the context of another task (e.g. as with CRIU), as otherwise the presence of an SVE signal context with SVE_SIG_FLAG_SM implies that TIF_SME is already set.

While in this state, task_fpsimd_load() will NOT configure SMCR_ELx (leaving some arbitrary value configured in hardware) before restoring SVCR and attempting to restore the streaming mode SVE registers from memory via sve_load_state(). As the value of SMCR_ELx.LEN may be larger than the task's streaming SVE vector length, this may read memory outside of the task's allocated sve_state, reading unrelated data and/or triggering a fault.

While this can result in secrets being loaded into streaming…

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CVE-2026-23102 — arm64/fpsimd: signal: Fix restoration of SVE context