riscv: errata: select RISCV_ALTERNATIVE_EARLY for THEAD GHOSTWRITE

Summary

In the Linux kernel, the following vulnerability has been resolved: riscv: errata: select RISCV_ALTERNATIVE_EARLY for THEAD GHOSTWRITE errata_probe_ghostwrite() only marks the CPU as vulnerable when it is called at the RISCV_ALTERNATIVES_EARLY_BOOT stage, and the mitigation in ghostwrite_enable_mitigation() only takes effect if the vulnerable state was recorded before the boot alternatives are patched. The early boot stage is only executed when CONFIG_RISCV_ALTERNATIVE_EARLY is enabled, which currently is only selected by ERRATA_THEAD_MAE. In a kernel built with ERRATA_THEAD_GHOSTWRITE=y but ERRATA_THEAD_MAE=n, the early alternatives never run, so ghostwrite_state is never set to VULNERABLE: ghostwrite_enable_mitigation() returns false, xtheadvector remains enabled, and sysfs reports "Not affected" on a vulnerable T-Head C9xx CPU. Select RISCV_ALTERNATIVE_EARLY from ERRATA_THEAD_GHOSTWRITE so that the vulnerability is detected in the early boot stage and the default mitigation is applied.

Timeline

1. Oct 23, 2026, 12:20 PM UTCCVE published
2. Oct 23, 2026, 12:45 PM UTCFirst seen by cve.now
3. Oct 24, 2026, 2:10 PM UTCRecord last updated

Affected versions

• Linux Linux

  From 4bf97069239bcfca9840936313c7ac35a6e04488 · fixed in fa465a7819ecbe5801b78c088d3cadaf2664b8ca; From 4bf97069239bcfca9840936313c7ac35a6e04488 · fixed in 7fee577a2fa78b9a76da015beec1ccf978746ebb; From 4bf97069239bcfca9840936313c7ac35a6e04488 · fixed in 298510bbc7c3017c0faf481c6ea66f1065b657b4

• Linux Linux

  6.14

• KernelLinux

  From 6.14.0 · fixed in 6.18.57; From 6.19.0 · fixed in 7.2.11

References 3