CVE-2026-93266: In the Linux kernel, the following vulnerability has been resolved: arm64: RSI: fix field-spanning write warning in attestation token init

Executive brief

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

arm64: RSI: fix field-spanning write warning in attestation token init

The challenge is passed in registers a1 through a8. However, copying to &regs.a1 makes FORTIFY treat the destination as the single a1 field, resulting in a field-spanning write warning. [1]

Overlay the SMCCC register structure with an RSI-specific argument layout and copy the challenge into an explicit 64-byte array. This keeps the existing a1-a8 argument encoding while giving the copy a correctly sized destination object.

[1] memcpy: detected field-spanning write (size 64) of single field "&regs.a1" at ./arch/arm64/include/asm/rsi_cmds.h:119 (size 8) WARNING: ./arch/arm64/include/asm/rsi_cmds.h:119 at rsi_attestation_token_init+0xdc/0xf8 [arm_cca_guest], CPU#0: cat/3314

References

• https://git.kernel.org/stable/c/221049874b6a78c7d87bc826581b0695cd338e2b
• https://git.kernel.org/stable/c/d29a8ee271da17b5e32d7a76a9c78d43f66447ca