[LTP] [PATCH v8 0/5] Reproducer for ghostlock

[Andrea Cervesato]

Test for CVE-2026-43499 (GhostLock), a stack use-after-free in the
rtmutex PI code, fixed in kernel v7.1:
3bfdc63936dd ("rtmutex: Use waiter::task instead of current in remove_waiter()")

Reproducer based on the Nebula Security writeup and open-sourced PoC
(https://nebusec.ai/research/ionstack-part-2/, https://github.com/NebuSec/CyberMeowfia).
Beware, this test will crash the system on a vulnerable kernel.

Assisted by Kimi K3 for the analysis and written mostly with Gemini Pro
3.1 Max.

Signed-off-by: Andrea Cervesato <andrea.cervesato@suse.com>
---
Changes in v8:
- remove PR_SET_MM_MAP_SIZE from commit message
- remove redundant assignment in ghostlock
- Link to v7: https://lore.kernel.org/20260903-cve-ghostlock-v7-0-771e99aa3057@suse.com

Changes in v7:
- wrap doc-comment lines in sched_setattr01 to stay under 80 columns
- allocate read_attr via .bufs in sched_getattr01
- keep const in sched_setattr() fallback prototype in lapi/sched.h
- update SAFE_SCHED_SETATTR() commit message to describe test usage and remove forward references
- remove unused PR_SET_MM_MAP_SIZE fallback definition from lapi/prctl.h
- wrap doc-comment lines in ghostlock.c to stay under 80 columns
- format multi-line comment in ghostlock.c spray loop
- add explanation comment for try_sizes[] in ghostlock.c
- check return values of TST_THREAD_STATE_WAIT() in ghostlock.c
- check futex_lock_pi() and futex_unlock_pi() returns, report ENOSYS as TCONF, and abort on errors
- add ENOSYS checks for FUTEX_WAIT_REQUEUE_PI and FUTEX_CMP_REQUEUE_PI in ghostlock.c
- Link to v6: https://lore.kernel.org/20260903-cve-ghostlock-v6-0-a3272bb81e4d@suse.com

Changes in v6:
- drop const from sched_setattr() and safe_sched_setattr() prototypes to match glibc 2.41+
- add kernel-doc comment for SAFE_SCHED_SETATTR()
- fix struct prctl_mm_map fallback guard in lapi/prctl.h
- validate futex_wait_requeue_pi() outcome before waking spray checkpoint
- sort ghostlock entry in testcases/cve/.gitignore
- Link to v5: https://lore.kernel.org/20260902-cve-ghostlock-v5-0-569b9eb37941@suse.com

Changes in v5:
- reduced synchronization checkpoints from 5 to 3
- introduced and used SAFE_SCHED_SETATTR() in lapi/sched.h
- dropped unused PR_SET_MM_MAP_SIZE probe in setup()
- fixed duplicated -pthread entry in Makefile
- fixed CVE numerical ordering in runtest/cve
- Link to v4: https://lore.kernel.org/20260826-cve-ghostlock-v4-0-52ec94d6635f@suse.com

Changes in v4:
- handle runtime inside the test
- increase futext wait so we don't TBROK before runtime
- comment prctl() syscall
- move static vars out of the run function
- Link to v3: https://lore.kernel.org/20260803-cve-ghostlock-v3-0-cde83fa429b7@suse.com

Changes in v3:
- improve sync mechanism
- fix lapi imports
- Link to v2: https://lore.kernel.org/20260803-cve-ghostlock-v2-0-b60588853140@suse.com

Changes in v2:
- fix build
- fix 32bit run
- Link to v1: https://lore.kernel.org/20260801-cve-ghostlock-v1-0-178f698f9702@suse.com

To: Linux Test Project <ltp@lists.linux.it>

---
Andrea Cervesato (5):
      sched_setattr01: Convert to new API
      sched_getattr01: Convert to new API
      lapi/sched: add SAFE_SCHED_SETATTR()
      lapi/prctl: add more fallback definitions
      cve: add CVE-2026-43499 reproducer

 configure.ac                                       |   2 +
 include/lapi/prctl.h                               |  24 ++
 include/lapi/sched.h                               |  29 +++
 runtest/cve                                        |   1 +
 testcases/cve/.gitignore                           |   1 +
 testcases/cve/Makefile                             |   2 +-
 testcases/cve/ghostlock.c                          | 277 +++++++++++++++++++++
 testcases/kernel/syscalls/sched_getattr/Makefile   |   1 -
 .../syscalls/sched_getattr/sched_getattr01.c       | 134 ++++------
 testcases/kernel/syscalls/sched_setattr/Makefile   |   1 -
 .../syscalls/sched_setattr/sched_setattr01.c       | 231 ++++++++++-------
 11 files changed, 529 insertions(+), 174 deletions(-)
---
base-commit: 12724413534a6d4160ff9694ba6f09daa4ccb6bd
change-id: 20260801-cve-ghostlock-6ee4b2f69fd6

Best regards,
--  
Andrea Cervesato <andrea.cervesato@suse.com>