CVE-2023-52926 io_uring/rw: split io_read() into a helper

In the Linux kernel, the following vulnerability has been resolved: IORINGOPREAD did not correctly consume the provided buffer list when read i/o returned 0 except for -EAGAIN and -EIOCBQUEUED return. This can lead to a potential use-after-free when the completion via iorwdone runs at separate...