CVE-2024-42265

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

protect the fetch of ->fd[fd] in do_dup2() from mispredictions

both callers have verified that fd is not greater than ->max_fds;

however, misprediction might end up with

tofree = fdt->fd[fd];

being speculatively executed. That's wrong for the same reasons

why it's wrong in close_fd()/file_close_fd_locked(); the same

solution applies - array_index_nospec(fd, fdt->max_fds) could differ

from fd only in case of speculative execution on mispredicted path.