From 8157f3e03107e77b8306d4ab1388a63548a13470 Mon Sep 17 00:00:00 2001
From: "H.J. Lu" <hjl.tools@gmail.com>
Date: Wed, 18 Oct 2017 17:18:37 -0700
Subject: [PATCH] Use dlsym to check if libdl is needed for plugin
config/plugins.m4 has
if test "$plugins" = "yes"; then
AC_SEARCH_LIBS([dlopen], [dl])
fi
Plugin uses dlsym, but libasan.so only intercepts dlopen, not dlsym:
[hjl@gnu-tools-1 binutils-text]$ nm -D /lib64/libasan.so.4| grep " dl"
0000000000038580 W dlclose
U dl_iterate_phdr
000000000004dc50 W dlopen
U dlsym
U dlvsym
[hjl@gnu-tools-1 binutils-text]$
Testing dlopen for libdl leads to false negative when -fsanitize=address
is used. It results in link failure:
../bfd/.libs/libbfd.a(plugin.o): undefined reference to symbol 'dlsym@@GLIBC_2.16'
dlsym should be used to check if libdl is needed for plugin.
* plugins.m4 (AC_PLUGINS): Use dlsym to check if libdl is needed.
@@ -16,6 +16,6 @@ AC_DEFUN([AC_PLUGINS],
[plugins=$maybe_plugins]
)
if test "$plugins" = "yes"; then
- AC_SEARCH_LIBS([dlopen], [dl])
+ AC_SEARCH_LIBS([dlsym], [dl])
fi
])