CVE-2022-48801

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

iio: buffer: Fix file related error handling in IIO_BUFFER_GET_FD_IOCTL

If we fail to copy the just created file descriptor to userland, we

try to clean up by putting back 'fd' and freeing 'ib'. The code uses

put_unused_fd() for the former which is wrong, as the file descriptor

was already published by fd_install() which gets called internally by

anon_inode_getfd().

This makes the error handling code leaving a half cleaned up file

descriptor table around and a partially destructed 'file' object,

allowing userland to play use-after-free tricks on us, by abusing

the still usable fd and making the code operate on a dangling

'file->private_data' pointer.

Instead of leaving the kernel in a partially corrupted state, don't

attempt to explicitly clean up and leave this to the process exit

path that'll release any still valid fds, including the one created

by the previous call to anon_inode_getfd(). Simply return -EFAULT to

indicate the error.