io_uring/waitid: clear waitid info before copying it to userspace

CVE-2026-46315

What is CVE-2026-46315?

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

io_uring/waitid: clear waitid info before copying it to userspace

IORING_OP_WAITID stores its result fields in struct io_waitid::info and later copies them to userspace siginfo. The prep path initializes the request arguments, but it does not initialize info itself.

If the wait operation completes without reporting a child event, the common wait code can return without writing wo_info. In that case io_waitid_finish() still copies iw->info to userspace, exposing stale bytes from the reused io_kiocb command storage.

Clear the result storage during prep so the io_uring path matches the regular waitid syscall, which uses a zero-initialized struct waitid_info.

References