[LTP] [PATCH v5 0/4] tst_kconfig: automatic module load/unload for CONFIG_*=m

[Li Wang]

From: "Li Wang (Hieco)" <li.wang@linux.dev>

Tests that depend on a config set to =m currently load the module
themselves, and may fail with misleading errors when it is missing,
e.g. bind() returning EADDRNOTAVAIL for AF_VSOCK without vsock_loopback.

This series makes tst_kconfig record the module for every
config_module_maps[] entry seen as =m, load them once the kernel
config check passes, and unload them at cleanup time.

Changes in v5:
- cve-2025-21756.c: merge drop_privileges into setup and drop cleanup.
- keyctl23.c: remove tst_modprobe() so it can run on Android.

Changes in v4:
- tst_kconfig: fold module_name_for_config() into
  kconfig_module_record()
- tst_kconfig: move the choice == 'm' gate into
  kconfig_module_record() and pass struct tst_kconfig_var * instead
  of the raw config name.

Changes in v3:
- Queue only configs that stay 'm' after kconfig_module_check(),
  so a module downgraded to 'n' does not abort an otherwise
  runnable test.
- Unload with "modprobe -r" instead of "rmmod" to also remove
  dependencies pulled in by modprobe.
- Drop the redundant geteuid() check in the unload path.
- Raise MAX_LOADED_MODULES from 16 to 32.
- cve-2025-21756: drop privileges to nobody after module loading
  and regain root in cleanup(), so the reproducer runs from a
  non-root context while the framework can still unload modules.

Changes in v2:
- Add tst_module_is_loaded() helper.
- Only load/unload modules that are not already loaded.
- Skip automatic loading when KCONFIG_SKIP_CHECK=1, keeping the
  semantics consistent with skipping the config check.
- Document the KCONFIG_SKIP_CHECK=1 behaviour for keyctl29/keyctl30
  and the vsock/vsock_loopback mapping.

Li Wang (Hieco) (4):
  lib: add module is loaded check
  tst_kconfig: load and unload kernel modules for CONFIG_*=m
  tst_kconfig: add module mappings for vsock/vsock_loopback
  testcases: drop manual tst_modprobe() now handled by tst_kconfig

 include/tst_kconfig.h                       | 28 ++++++++
 include/tst_module.h                        |  1 +
 lib/tst_kconfig.c                           | 77 +++++++++++++++++++++
 lib/tst_module.c                            | 39 +++++++++++
 lib/tst_test.c                              | 11 ++-
 testcases/cve/cve-2025-21756.c              | 17 +++++
 testcases/cve/cve-2026-46331.c              |  7 --
 testcases/cve/sctphantom.c                  |  3 -
 testcases/kernel/syscalls/keyctl/keyctl23.c |  5 --
 testcases/kernel/syscalls/keyctl/keyctl29.c |  3 -
 testcases/kernel/syscalls/keyctl/keyctl30.c |  3 -
 11 files changed, 171 insertions(+), 23 deletions(-)

-- 
2.56.0