Executive brief
In the Linux kernel, the following vulnerability has been resolved:
ntfs: propagate reparse index insertion failure
update_reparse_data() ignores the return value of set_reparse_index(). When index insertion fails, the code removes the just-written reparse data as cleanup but still returns 0, so symlink(2) (and WSL special file creation) reports success while no reparse data exists on disk. When there was no previous reparse data (oldsize == 0), the failure was likewise silently ignored.
Propagate the error to the caller.