ci(quality-runners): lower ASLR entropy for ThreadSanitizer tests

The mpmc_concurrent_queue_tsan_test in score_lifecycle_health aborts with
'FATAL: ThreadSanitizer: unexpected memory mapping' on Ubuntu 24.04 runners,
where vm.mmap_rnd_bits defaults to 32. That high ASLR entropy is incompatible
with the sanitizer shadow-memory layout. Lower it to 28 before running the
unit tests (google/sanitizers#1614). Best-effort so local runs are unaffected.

Author: antonkri

scripts/quality_runners.py

@@ -17,7 +17,7 @@
 from dataclasses import dataclass
 from pathlib import Path
 from pprint import pprint
-from subprocess import PIPE, Popen
+from subprocess import PIPE, Popen, run
 
 from known_good.models.known_good import load_known_good
 from known_good.models.module import Module
@@ -34,6 +34,31 @@ def print_centered(message: str, width: int = 120, fillchar: str = "-") -> None:
     print(message.center(width, fillchar))
 
 
+def configure_aslr_for_sanitizers() -> None:
+    """Lower ASLR entropy so ThreadSanitizer/ASan tests can run.
+
+    Modern kernels (e.g. Ubuntu 24.04 CI runners) default ``vm.mmap_rnd_bits``
+    to 32. That is incompatible with the sanitizer shadow-memory layout and
+    makes ThreadSanitizer abort before any test runs with
+    ``FATAL: ThreadSanitizer: unexpected memory mapping``. Lowering the value
+    to 28 is the documented workaround (see google/sanitizers#1614).
+
+    Best-effort: silently ignored when sudo/sysctl is unavailable or the value
+    is already low enough, so local runs without privileges are unaffected.
+    """
+    print_centered("QR: Configuring ASLR entropy for sanitizer tests")
+    result = run(
+        ["sudo", "sysctl", "-w", "vm.mmap_rnd_bits=28"],
+        capture_output=True,
+        text=True,
+        check=False,
+    )
+    if result.returncode == 0:
+        print(result.stdout.strip())
+    else:
+        print(f"QR: Could not lower vm.mmap_rnd_bits (continuing anyway): {result.stderr.strip()}")
+
+
 def run_unit_test_with_coverage(module: Module) -> dict[str, str | int]:
     print_centered("QR: Running unit tests")
 
@@ -282,6 +307,7 @@ def parse_arguments() -> argparse.Namespace:
 
 def main() -> bool:
     args = parse_arguments()
+    configure_aslr_for_sanitizers()
     args.coverage_output_dir.mkdir(parents=True, exist_ok=True)
     path_to_docs = Path(__file__).parent.parent / "docs/verification_report"
     path_to_docs.mkdir(parents=True, exist_ok=True)