# HG changeset patch
# User Sam Lantinga <slouken@libsdl.org>
# Date 1541207231 25200
# Node ID 60f322c5984f6486677775afead83d1ea559f451
# Parent  5817dbd756190d97c0d58342fde175e45e13ec3e
Fixed bug 4308 - Prebuilt SDL.dll files not compiled with ASLR support (DYNAMICBASE)

Cameron Gutman

The current SDL 2.0.8 and the prerelease SDL 2.0.9 are compiled without the DYNAMICBASE flag to indicate that ASLR may relocate the DLL at load-time. https://docs.microsoft.com/en-us/cpp/build/reference/dynamicbase-use-address-space-layout-randomization?view=vs-2017

When I build SDL.dll myself using the VS2010 project, the DLL has the DYNAMICBASE flag set (as is the default). Similarly, MinGW-w64 also enables ASLR by default on all binaries for a couple years now (https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=836365)

diff -r 5817dbd75619 -r 60f322c5984f configure
--- a/configure	Fri Nov 02 17:25:00 2018 -0700
+++ b/configure	Fri Nov 02 18:07:11 2018 -0700
@@ -16063,6 +16063,108 @@
 { $as_echo "$as_me:${as_lineno-$LINENO}: result: $have_no_undefined" >&5
 $as_echo "$have_no_undefined" >&6; }
 
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker option --dynamicbase" >&5
+$as_echo_n "checking for linker option --dynamicbase... " >&6; }
+have_dynamicbase=no
+case "$host" in
+    *)
+        save_LDFLAGS="$LDFLAGS"
+        LDFLAGS="$LDFLAGS -Wl,--dynamicbase"
+        cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+
+int
+main ()
+{
+
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_link "$LINENO"; then :
+
+        have_dynamicbase=yes
+        EXTRA_LDFLAGS="$EXTRA_LDFLAGS -Wl,--dynamicbase"
+
+fi
+rm -f core conftest.err conftest.$ac_objext \
+    conftest$ac_exeext conftest.$ac_ext
+        LDFLAGS="$save_LDFLAGS"
+        ;;
+esac
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $have_dynamicbase" >&5
+$as_echo "$have_dynamicbase" >&6; }
+
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker option --nxcompat" >&5
+$as_echo_n "checking for linker option --nxcompat... " >&6; }
+have_nxcompat=no
+case "$host" in
+    *)
+        save_LDFLAGS="$LDFLAGS"
+        LDFLAGS="$LDFLAGS -Wl,--nxcompat"
+        cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+
+int
+main ()
+{
+
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_link "$LINENO"; then :
+
+        have_nxcompat=yes
+        EXTRA_LDFLAGS="$EXTRA_LDFLAGS -Wl,--nxcompat"
+
+fi
+rm -f core conftest.err conftest.$ac_objext \
+    conftest$ac_exeext conftest.$ac_ext
+        LDFLAGS="$save_LDFLAGS"
+        ;;
+esac
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $have_nxcompat" >&5
+$as_echo "$have_nxcompat" >&6; }
+
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker option --high-entropy-va" >&5
+$as_echo_n "checking for linker option --high-entropy-va... " >&6; }
+have_high_entropy_va=no
+case "$host" in
+    *)
+        save_LDFLAGS="$LDFLAGS"
+        LDFLAGS="$LDFLAGS -Wl,--high-entropy-va"
+        cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+
+int
+main ()
+{
+
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_link "$LINENO"; then :
+
+        have_high_entropy_va=yes
+        EXTRA_LDFLAGS="$EXTRA_LDFLAGS -Wl,--high-entropy-va"
+
+fi
+rm -f core conftest.err conftest.$ac_objext \
+    conftest$ac_exeext conftest.$ac_ext
+        LDFLAGS="$save_LDFLAGS"
+        ;;
+esac
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $have_high_entropy_va" >&5
+$as_echo "$have_high_entropy_va" >&6; }
+
 # Check whether --enable-libc was given.
 if test "${enable_libc+set}" = set; then :
   enableval=$enable_libc;
diff -r 5817dbd75619 -r 60f322c5984f configure.in
--- a/configure.in	Fri Nov 02 17:25:00 2018 -0700
+++ b/configure.in	Fri Nov 02 18:07:11 2018 -0700
@@ -232,6 +232,57 @@
 esac
 AC_MSG_RESULT($have_no_undefined)
 
+AC_MSG_CHECKING(for linker option --dynamicbase)
+have_dynamicbase=no
+case "$host" in
+    *)
+        save_LDFLAGS="$LDFLAGS"
+        LDFLAGS="$LDFLAGS -Wl,--dynamicbase"
+        AC_TRY_LINK([
+        ],[
+        ],[
+        have_dynamicbase=yes
+        EXTRA_LDFLAGS="$EXTRA_LDFLAGS -Wl,--dynamicbase"
+        ])
+        LDFLAGS="$save_LDFLAGS"
+        ;;
+esac
+AC_MSG_RESULT($have_dynamicbase)
+
+AC_MSG_CHECKING(for linker option --nxcompat)
+have_nxcompat=no
+case "$host" in
+    *)
+        save_LDFLAGS="$LDFLAGS"
+        LDFLAGS="$LDFLAGS -Wl,--nxcompat"
+        AC_TRY_LINK([
+        ],[
+        ],[
+        have_nxcompat=yes
+        EXTRA_LDFLAGS="$EXTRA_LDFLAGS -Wl,--nxcompat"
+        ])
+        LDFLAGS="$save_LDFLAGS"
+        ;;
+esac
+AC_MSG_RESULT($have_nxcompat)
+
+AC_MSG_CHECKING(for linker option --high-entropy-va)
+have_high_entropy_va=no
+case "$host" in
+    *)
+        save_LDFLAGS="$LDFLAGS"
+        LDFLAGS="$LDFLAGS -Wl,--high-entropy-va"
+        AC_TRY_LINK([
+        ],[
+        ],[
+        have_high_entropy_va=yes
+        EXTRA_LDFLAGS="$EXTRA_LDFLAGS -Wl,--high-entropy-va"
+        ])
+        LDFLAGS="$save_LDFLAGS"
+        ;;
+esac
+AC_MSG_RESULT($have_high_entropy_va)
+
 dnl See whether we are allowed to use the system C library
 AC_ARG_ENABLE(libc,
 AC_HELP_STRING([--enable-libc], [Use the system C library [[default=yes]]]),