CVE-2024-35880

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

io_uring/kbuf: hold io_buffer_list reference over mmap

If we look up the kbuf, ensure that it doesn't get unregistered until

after we're done with it. Since we're inside mmap, we cannot safely use

the io_uring lock. Rely on the fact that we can lookup the buffer list

under RCU now and grab a reference to it, preventing it from being

unregistered until we're done with it. The lookup returns the

io_buffer_list directly with it referenced.