From 5713c2ffdd7f0c701d7edb468d07f6cea5cd8770 Mon Sep 17 00:00:00 2001
From: Timothy Flynn <trflynn89@pm.me>
Date: Tue, 12 Mar 2024 19:53:15 -0400
Subject: [PATCH] CI: Work around a libasan bug seen on Ubuntu with the Linux
 6.5 kernel

We are recently seeing SEGV crashes during the build (while running code
generators) from within libasan itself. Turns out this is libasan bug
seen with the Linux 6.5 kernel on Ubuntu.
---
 Meta/Azure/Lagom.yml | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/Meta/Azure/Lagom.yml b/Meta/Azure/Lagom.yml
index 514f2f2824..630baf9a53 100644
--- a/Meta/Azure/Lagom.yml
+++ b/Meta/Azure/Lagom.yml
@@ -58,6 +58,15 @@ jobs:
           ccache_version: 2
         serenity_ccache_size: '2G'
 
+    # On Ubuntu, with Linux kernel 6.5, ARCH_MMAP_RND_BITS was changed from ARCH_MMAP_RND_BITS_MIN (28 on x64) to
+    # ARCH_MMAP_RND_BITS_MAX (32 on x64). This breaks assumptions made by libasan's allocators, and we see a flaky
+    # crash from within libasan itself. Here, we restore the previous value until we have a version of GCC which fixes
+    # the issue in libasan (reportedly 13.2.1): https://stackoverflow.com/questions/77894856/possible-bug-in-gcc-sanitizers
+    - ${{ if eq(parameters.os, 'Linux') }}:
+      - script: |
+          sudo sysctl vm.mmap_rnd_bits=28
+        displayName: 'Work around libasan ASLR bug'
+
     - ${{ if eq(parameters.os, 'Android') }}:
       - script: |
           yes | $ANDROID_SDK_ROOT/tools/bin/sdkmanager "ndk;$(ndk_version)"