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

io_uring: prevent reg-wait speculations

With *ENTER_EXT_ARG_REG instead of passing a user pointer with arguments
for the waiting loop the user can specify an offset into a pre-mapped
region of memory, in which case the
[offset, offset + sizeof(io_uring_reg_wait)) will be intepreted as the
argument.

As we address a kernel array using a user given index, it'd be a subject
to speculation type of exploits. Use array_index_nospec() to prevent
that. Make sure to pass not the full region size but truncate by the
maximum offset allowed considering the structure size.

https://git.kernel.org/stable/c/29b95ac917927ce9f95bf38797e16333ecb489b1

https://git.kernel.org/stable/c/2a6de94df7bfa76d9850443547e7b3333f63a16a