From b3cff3cea4c398073a26b8092f61ae32f99c827d Mon Sep 17 00:00:00 2001
From: Adam Perry <anp@openai.com>
Date: Wed, 27 May 2026 22:51:59 +0000
Subject: [PATCH] Disable Zig UBSan and fence musl pkg-config lookup

---
 .github/scripts/install-musl-build-tools.sh | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/.github/scripts/install-musl-build-tools.sh b/.github/scripts/install-musl-build-tools.sh
index e4c6683d0e..b005d42437 100644
--- a/.github/scripts/install-musl-build-tools.sh
+++ b/.github/scripts/install-musl-build-tools.sh
@@ -150,7 +150,9 @@ for arg in "\$@"; do
   args+=("\${arg}")
 done
 
-exec "${zig_bin}" cc -target "${zig_target}" "\${args[@]}"
+# Zig enables UBSan for debug C builds by default. Rust links these objects
+# without Zig's sanitizer runtime, so keep native dependencies uninstrumented.
+exec "${zig_bin}" cc -target "${zig_target}" -fno-sanitize=undefined "\${args[@]}"
 EOF
   cat >"${cxx}" <<EOF
 #!/usr/bin/env bash
@@ -207,7 +209,9 @@ for arg in "\$@"; do
   args+=("\${arg}")
 done
 
-exec "${zig_bin}" c++ -target "${zig_target}" "\${args[@]}"
+# Zig enables UBSan for debug C++ builds by default. Rust links these objects
+# without Zig's sanitizer runtime, so keep native dependencies uninstrumented.
+exec "${zig_bin}" c++ -target "${zig_target}" -fno-sanitize=undefined "\${args[@]}"
 EOF
   chmod +x "${cc}" "${cxx}"
 
@@ -270,6 +274,11 @@ echo "PKG_CONFIG_PATH=${pkg_config_path}" >> "$GITHUB_ENV"
 pkg_config_path_var="PKG_CONFIG_PATH_${TARGET}"
 pkg_config_path_var="${pkg_config_path_var//-/_}"
 echo "${pkg_config_path_var}=${libcap_pkgconfig_dir}" >> "$GITHUB_ENV"
+pkg_config_libdir_var="PKG_CONFIG_LIBDIR_${TARGET}"
+pkg_config_libdir_var="${pkg_config_libdir_var//-/_}"
+# Do not let musl cross-builds resolve native libraries from the host glibc
+# pkg-config directories. libcap is the only target package provided here.
+echo "${pkg_config_libdir_var}=${libcap_pkgconfig_dir}" >> "$GITHUB_ENV"
 
 if [[ -n "${sysroot}" && "${sysroot}" != "/" ]]; then
   echo "PKG_CONFIG_SYSROOT_DIR=${sysroot}" >> "$GITHUB_ENV"