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

9p: Fix v9fs_issue_write() to update i_size and remote_i_size

Fix v9fs_issue_write() to update i_size and remote_i_size to the new size
of the server file if we made it larger, using the start fpos and the count
returned by p9_client_write() to calculate the new minimum file size.

This assumes that if the 9P server makes a short write (say it hits
ENOSPC), a reduced count is returned.