CVE-2025-21988

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

fs/netfs/read_collect: add to next->prev_donated

If multiple subrequests donate data to the same "next" request
(depending on the subrequest completion order), each of them would
overwrite the `prev_donated` field, causing data corruption and a
BUG() crash ("Can't donate prior to front").