use kfree_rcu to release ops

Summary

In the Linux kernel, the following vulnerability has been resolved: netfilter: nat: use kfree_rcu to release ops Florian Westphal says: "Historically this is not an issue, even for normal base hooks: the data path doesn't use the original nf_hook_ops that are used to register the callbacks. However, in v5.14 I added the ability to dump the active netfilter hooks from userspace. This code will peek back into the nf_hook_ops that are available at the tail of the pointer-array blob used by the datapath. The nat hooks are special, because they are called indirectly from the central nat dispatcher hook. They are currently invisible to the nfnl hook dump subsystem though. But once that changes the nat ops structures have to be deferred too." Update nf_nat_register_fn() to deal with partial exposition of the hooks from error path which can be also an issue for nfnetlink_hook. A flaw was found in the Linux kernel's netfilter component, specifically within the Network Address Translation (NAT) subsystem. This vulnerability involves improper memory management when releasing network filter operation structures. This could potentially allow an attacker to cause a system crash, leading to a Denial of Service (DoS), or to gain unauthorized access to sensitive information due to the partial exposure of internal hook data during error handling. Red Hat severity: Important — CVSS 7 (CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H). Weakness: CWE-763. No fixing RHSA erratum has published yet; monitor the Red Hat CVE page and patch when it ships.