riscv: Sanitize syscall table indexing under speculation

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: riscv: Sanitize syscall table indexing under speculation The syscall number is a user-controlled value used to index into the syscall table. Use array_index_nospec() to clamp this value after the bounds check to prevent speculative out-of-bounds access and subsequent data leakage via cache side channels.

References

• https://git.kernel.org/stable/c/33743ec6679aa364ee19d1afbaa50593e9e6e443
• https://git.kernel.org/stable/c/c45848936ebdb4fcab92f8c39510db83c16d0239
• https://git.kernel.org/stable/c/8b44e753795107a22ba31495686e83f4aca48f36
• https://git.kernel.org/stable/c/25fd7ee7bf58ac3ec7be3c9f82ceff153451946c