High [CVE-2026-53270] clear the svc scheduler ptr early on edit

In the Linux kernel, the following vulnerability has been resolved: ipvs: clear the svc scheduler ptr early on edit ip_vs_edit_service() while unbinding the old scheduler clears the svc->scheduler ptr after the scheduler module initiates RCU callbacks.

This can cause packets to use the old scheduler at the time when svc->sched_data is already freed after RCU grace period. Fix it by clearing the ptr early in ip_vs_unbind_scheduler(), before the done_service method schedules any RCU callbacks.

Also, if the new scheduler fails to initialize when replacing the old scheduler, try to restore the old scheduler while still returning the error code. A flaw was found in the Linux kernel's IP Virtual Server (IPVS) component.

During the `ip_vs_edit_service()` operation, the `svc->scheduler` pointer is cleared too late when unbinding an old scheduler. This improper handling allows packets to access previously freed scheduler data, leading to a use-after-free vulnerability.

This can result in system instability or a denial of service. Red Hat severity: Moderate — CVSS 7 (CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H).

Weakness: CWE-825. Affected Red Hat products: Red Hat Enterprise Linux 8; Red Hat Enterprise Linux 10; Red Hat Enterprise Linux 6; Red Hat Enterprise Linux 7; Red Hat Enterprise Linux 9.

Will not fix / out of support: Red Hat Enterprise Linux 6.