CVE-2025-21726padata: avoid UAF for reorder_work

Official description

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 <kworker context> invoke_padata_reorder // UAF of 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.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/f4f1b1169fc3694f9bc3e28c6c68dbbf4cc744c0
• https://git.kernel.org/stable/c/4c6209efea2208597dbd3e52dc87a0d1a8f2dbe1
• https://git.kernel.org/stable/c/7000507bb0d2ceb545c0a690e0c707c897d102c2
• https://git.kernel.org/stable/c/6f45ef616775b0ce7889b0f6077fc8d681ab30bc
• https://git.kernel.org/stable/c/8ca38d0ca8c3d30dd18d311f1a7ec5cb56972cac
• https://git.kernel.org/stable/c/a54091c24220a4cd847d5b4f36d678edacddbaf0
• https://git.kernel.org/stable/c/dd7d37ccf6b11f3d95e797ebe4e9e886d0332600
• https://lists.debian.org/debian-lts-announce/2025/05/msg00030.html
• https://lists.debian.org/debian-lts-announce/2025/03/msg00028.html
• https://cert-portal.siemens.com/productcert/html/ssa-265688.html
• https://cert-portal.siemens.com/productcert/html/ssa-784472.html