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

padata: avoid UAF for reorder_work

Although the previous patch can avoid ps and ps UAF for _do_serial, it
can not avoid potential UAF issue for reorder_work. This issue can
happen just as below:

crypto_request crypto_request crypto_del_alg
padata_do_serial
...
padata_reorder
// processes all remaining
// requests then breaks
while (1) {
if (!padata)
break;
...
}

			padata_do_serial
			  // new request added
			  list_add
// sees the new request
queue_work(reorder_work)
			  padata_reorder
			    queue_work_on(squeue->work)

...

			<kworker context>
			padata_serial_worker
			// completes new request,
			// no more outstanding
			// requests

						crypto_del_alg
						  // free pd

To avoid UAF for 'reorder_work', get 'pd' ref before put 'reorder_work'
into the 'serial_wq' and put 'pd' ref until the 'serial_wq' finish.

References

• https://nvd.nist.gov/vuln/detail/CVE-2025-21726
• https://git.kernel.org/stable/c/6f45ef616775b0ce7889b0f6077fc8d681ab30bc
• https://git.kernel.org/stable/c/7000507bb0d2ceb545c0a690e0c707c897d102c2
• https://git.kernel.org/stable/c/8ca38d0ca8c3d30dd18d311f1a7ec5cb56972cac
• https://git.kernel.org/stable/c/a54091c24220a4cd847d5b4f36d678edacddbaf0
• https://git.kernel.org/stable/c/dd7d37ccf6b11f3d95e797ebe4e9e886d0332600