Important: kernel security update (Oracle Linux 8)

[4.18.0-553.137.1]
- Update Oracle Linux certificates (Kevin Lyons)
- Disable signing for aarch64 (Ilya Okomin)
- Oracle Linux RHCK Module Signing Key was added to the kernel trusted keys list (olkmod_signing_key.pem) [Orabug: 29539237]
- Update x509.genkey [Orabug: 24817676]
- Conflict with shim-ia32 and shim-x64 <= 15.3-1.0.3
- Remove upstream reference during boot (Kevin Lyons) [Orabug: 34750652]
- Add new Oracle Linux Driver Signing (key 1) certificate [Orabug: 37985772]
- Update Oracle Linux certificates (Kevin Lyons)
- Disable signing for aarch64 (Ilya Okomin)
- Oracle Linux RHCK Module Signing Key was added to the kernel trusted keys list (olkmod_signing_key.pem) [Orabug: 29539237]
- Update x509.genkey [Orabug: 24817676]
- Conflict with shim-ia32 and shim-x64 <= 15.3-1.0.3
- Remove upstream reference during boot (Kevin Lyons) [Orabug: 34750652]
- Add new Oracle Linux Driver Signing (key 1) certificate [Orabug: 37985772]

[4.18.0-553.137.1]
- selinux: RHEL-only hotfix for execmem regression (Ondrej Mosnacek) [RHEL-179435] {CVE-2026-46054}
- selinux: fix overlayfs mmap() and mprotect() access checks (Ondrej Mosnacek) [RHEL-179435] {CVE-2026-46054}
- lsm: add backing_file LSM hooks (Ondrej Mosnacek) [RHEL-179435] {CVE-2026-46054}
- fs: prepare for adding LSM blob to backing_file (Ondrej Mosnacek) [RHEL-179435] {CVE-2026-46054}
- perf/core: Fix MMAP event path names with backing files (Ondrej Mosnacek) [RHEL-179435]
- fs: constify file ptr in backing_file accessor helpers (Ondrej Mosnacek) [RHEL-179435] {CVE-2026-46054}
- ovl: Fix nested backing file paths (Ondrej Mosnacek) [RHEL-179435]
- fs: store real path instead of fake path in backing file f_path (Ondrej Mosnacek) [RHEL-179435]
- fs: create helper file_user_path() for user displayed mapped file path (Ondrej Mosnacek) [RHEL-179435]
- fs: get mnt_writers count for an open backing file's real path (Ondrej Mosnacek) [RHEL-179435]
- fs: move cleanup from init_file() into its callers (Ondrej Mosnacek) [RHEL-179435]
- fs: use backing_file container for internal files with 'fake' f_path (Ondrej Mosnacek) [RHEL-179435]
- fs: move kmem_cache_zalloc() into alloc_empty_file*() helpers (Ondrej Mosnacek) [RHEL-179435]
- ovl: pass layer mnt to ovl_open_realfile() (Ondrej Mosnacek) [RHEL-179435]