From 30b99d798f9728a96d4766dd3f7fcfe5daae8945 Mon Sep 17 00:00:00 2001
From: Roland McGrath <roland@hack.frob.com>
Date: Mon, 14 May 2012 16:08:25 -0700
Subject: [PATCH] BZ#10375: Configure magic to use -fno-stack-protector if
 needed.

---
 ChangeLog      |   9 ++++
 Makeconfig     |   2 +-
 NEWS           |  28 +++++-----
 config.make.in |   1 +
 configure      | 139 +++++++++++++++++++++++++++++++++++++++++++++++++
 configure.in   |  34 ++++++++++++
 6 files changed, 198 insertions(+), 15 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index cde0173851..ecfdebcc13 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,14 @@
 2012-05-16  Roland McGrath  <roland@hack.frob.com>
 
+	[BZ #10375]
+	* configure.in (NM): Add AC_CHECK_TOOL for it.
+	(libc_extra_cflags): New substituted variable.
+	Check for -fstack-protector being used implicitly.
+	* configure: Regenerated.
+	* config.make.in (config-extra-cflags): New variable,
+	gets @libc_extra_cflags@.
+	* Makeconfig (CFLAGS): Add $(config-extra-cflags) near the front.
+
 	[BZ #10375]
 	* configure.in: Check for _FORTIFY_SOURCE being predefined.
 	(CPPUNDEFS): New substituted variable; add -U_FORTIFY_SOURCE if needed.
diff --git a/Makeconfig b/Makeconfig
index b81594f077..3a09764dfa 100644
--- a/Makeconfig
+++ b/Makeconfig
@@ -668,7 +668,7 @@ CPPFLAGS = $(CPPUNDEFS) $(CPPFLAGS-config) $($(subdir)-CPPFLAGS) \
 	   $(foreach lib,$(libof-$(basename $(@F))) \
 			 $(libof-$(<F)) $(libof-$(@F)),$(CPPFLAGS-$(lib))) \
 	   $(CPPFLAGS-$(<F)) $(CPPFLAGS-$(@F)) $(CPPFLAGS-$(basename $(@F)))
-override CFLAGS	= -std=gnu99 $(gnu89-inline-CFLAGS) \
+override CFLAGS	= -std=gnu99 $(gnu89-inline-CFLAGS) $(config-extra-cflags) \
 		  $(filter-out %frame-pointer,$(+cflags)) $(+gccwarn-c) \
 		  $(sysdep-CFLAGS) $(CFLAGS-$(suffix $@)) $(CFLAGS-$(<F)) \
 		  $(CFLAGS-$(@F)) \
diff --git a/NEWS b/NEWS
index dc0f11ae1c..8d98497032 100644
--- a/NEWS
+++ b/NEWS
@@ -14,20 +14,20 @@ Version 2.16
   3440, 3748, 3768, 3866, 3868, 3906, 3976, 3992, 4026, 4108, 4596, 4822,
   5077, 5461, 5805, 5993, 6471, 6486, 6578, 6649, 6730, 6770, 6794, 6884,
   6890, 6894, 6895, 6907, 6911, 6959, 7064, 9739, 9902, 10110, 10135, 10140,
-  10153, 10210, 10254, 10346, 10545, 10716, 11174, 11322, 11365, 11451,
-  11494, 11521, 11677, 11837, 11959, 12047, 12097, 12193, 12297, 12298,
-  12301, 12340, 12354, 13058, 13361, 13525, 13526, 13527, 13528, 13529,
-  13530, 13531, 13532, 13533, 13547, 13551, 13552, 13553, 13555, 13556,
-  13559, 13563, 13566, 13583, 13592, 13594, 13613, 13618, 13637, 13656,
-  13658, 13673, 13691, 13695, 13704, 13705, 13706, 13726, 13738, 13739,
-  13750, 13758, 13760, 13761, 13775, 13786, 13787, 13792, 13806, 13824,
-  13840, 13841, 13844, 13846, 13851, 13852, 13854, 13871, 13872, 13873,
-  13879, 13883, 13884, 13885, 13886, 13892, 13895, 13908, 13910, 13911,
-  13912, 13913, 13914, 13915, 13916, 13917, 13918, 13919, 13920, 13921,
-  13922, 13923, 13924, 13926, 13927, 13928, 13938, 13941, 13942, 13954,
-  13955, 13956, 13963, 13967, 13970, 13973, 13979, 13983, 13986, 14012,
-  14027, 14033, 14034, 14040, 14043, 14044, 14049, 14053, 14055, 14064,
-  14080, 14083, 14103, 14104, 14109
+  10153, 10210, 10254, 10346, 10375 10545, 10716, 11174, 11322, 11365,
+  11451, 11494, 11521, 11677, 11837, 11959, 12047, 12097, 12193, 12297,
+  12298, 12301, 12340, 12354, 13058, 13361, 13525, 13526, 13527, 13528,
+  13529, 13530, 13531, 13532, 13533, 13547, 13551, 13552, 13553, 13555,
+  13556, 13559, 13563, 13566, 13583, 13592, 13594, 13613, 13618, 13637,
+  13656, 13658, 13673, 13691, 13695, 13704, 13705, 13706, 13726, 13738,
+  13739, 13750, 13758, 13760, 13761, 13775, 13786, 13787, 13792, 13806,
+  13824, 13840, 13841, 13844, 13846, 13851, 13852, 13854, 13871, 13872,
+  13873, 13879, 13883, 13884, 13885, 13886, 13892, 13895, 13908, 13910,
+  13911, 13912, 13913, 13914, 13915, 13916, 13917, 13918, 13919, 13920,
+  13921, 13922, 13923, 13924, 13926, 13927, 13928, 13938, 13941, 13942,
+  13954, 13955, 13956, 13963, 13967, 13970, 13973, 13979, 13983, 13986,
+  14012, 14027, 14033, 14034, 14040, 14043, 14044, 14049, 14053, 14055,
+  14064, 14080, 14083, 14103, 14104, 14109
 
 * ISO C11 support:
 
diff --git a/config.make.in b/config.make.in
index 4fa26081ff..f0db19929b 100644
--- a/config.make.in
+++ b/config.make.in
@@ -34,6 +34,7 @@ config-sysdirs = @sysnames@
 cflags-cpu = @libc_cv_cc_submachine@
 asflags-cpu = @libc_cv_cc_submachine@
 
+config-extra-cflags = @libc_extra_cflags@
 config-cflags-sse4 = @libc_cv_cc_sse4@
 config-cflags-avx = @libc_cv_cc_avx@
 config-cflags-sse2avx = @libc_cv_cc_sse2avx@
diff --git a/configure b/configure
index c295277e40..f23c40f99d 100755
--- a/configure
+++ b/configure
@@ -632,6 +632,7 @@ libc_cv_localedir
 libc_cv_slibdir
 old_glibc_headers
 libc_cv_gcc_unwind_find_fde
+libc_extra_cflags
 CPPUNDEFS
 sizeof_long_double
 EGREP
@@ -666,6 +667,7 @@ libc_cv_gcc_static_libgcc
 CXX_SYSINCLUDES
 SYSINCLUDES
 AUTOCONF
+NM
 READELF
 SED
 MAKEINFO
@@ -5154,6 +5156,98 @@ else
   READELF="$ac_cv_prog_READELF"
 fi
 
+if test -n "$ac_tool_prefix"; then
+  # Extract the first word of "${ac_tool_prefix}nm", so it can be a program name with args.
+set dummy ${ac_tool_prefix}nm; ac_word=$2
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for $ac_word" >&5
+$as_echo_n "checking for $ac_word... " >&6; }
+if ${ac_cv_prog_NM+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  if test -n "$NM"; then
+  ac_cv_prog_NM="$NM" # Let the user override the test.
+else
+as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
+for as_dir in $PATH
+do
+  IFS=$as_save_IFS
+  test -z "$as_dir" && as_dir=.
+    for ac_exec_ext in '' $ac_executable_extensions; do
+  if { test -f "$as_dir/$ac_word$ac_exec_ext" && $as_test_x "$as_dir/$ac_word$ac_exec_ext"; }; then
+    ac_cv_prog_NM="${ac_tool_prefix}nm"
+    $as_echo "$as_me:${as_lineno-$LINENO}: found $as_dir/$ac_word$ac_exec_ext" >&5
+    break 2
+  fi
+done
+  done
+IFS=$as_save_IFS
+
+fi
+fi
+NM=$ac_cv_prog_NM
+if test -n "$NM"; then
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: $NM" >&5
+$as_echo "$NM" >&6; }
+else
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
+$as_echo "no" >&6; }
+fi
+
+
+fi
+if test -z "$ac_cv_prog_NM"; then
+  ac_ct_NM=$NM
+  # Extract the first word of "nm", so it can be a program name with args.
+set dummy nm; ac_word=$2
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for $ac_word" >&5
+$as_echo_n "checking for $ac_word... " >&6; }
+if ${ac_cv_prog_ac_ct_NM+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  if test -n "$ac_ct_NM"; then
+  ac_cv_prog_ac_ct_NM="$ac_ct_NM" # Let the user override the test.
+else
+as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
+for as_dir in $PATH
+do
+  IFS=$as_save_IFS
+  test -z "$as_dir" && as_dir=.
+    for ac_exec_ext in '' $ac_executable_extensions; do
+  if { test -f "$as_dir/$ac_word$ac_exec_ext" && $as_test_x "$as_dir/$ac_word$ac_exec_ext"; }; then
+    ac_cv_prog_ac_ct_NM="nm"
+    $as_echo "$as_me:${as_lineno-$LINENO}: found $as_dir/$ac_word$ac_exec_ext" >&5
+    break 2
+  fi
+done
+  done
+IFS=$as_save_IFS
+
+fi
+fi
+ac_ct_NM=$ac_cv_prog_ac_ct_NM
+if test -n "$ac_ct_NM"; then
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_ct_NM" >&5
+$as_echo "$ac_ct_NM" >&6; }
+else
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
+$as_echo "no" >&6; }
+fi
+
+  if test "x$ac_ct_NM" = x; then
+    NM="false"
+  else
+    case $cross_compiling:$ac_tool_warned in
+yes:)
+{ $as_echo "$as_me:${as_lineno-$LINENO}: WARNING: using cross tools not prefixed with host triplet" >&5
+$as_echo "$as_me: WARNING: using cross tools not prefixed with host triplet" >&2;}
+ac_tool_warned=yes ;;
+esac
+    NM=$ac_ct_NM
+  fi
+else
+  NM="$ac_cv_prog_NM"
+fi
+
 
 for ac_prog in autoconf
 do
@@ -7577,6 +7671,51 @@ if test $libc_cv_predef_fortify_source = yes; then
 fi
 
 
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CC implicitly enables -fstack-protector" >&5
+$as_echo_n "checking whether $CC implicitly enables -fstack-protector... " >&6; }
+if ${libc_cv_predef_stack_protector+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+extern void foobar (char *);
+int
+main ()
+{
+char large_array[2048]; foobar (large_array);
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+
+libc_undefs=`$NM -u conftest.o |
+  LC_ALL=C $AWK '$1 == "U" { print $2 | "sort -u"; next } { exit(1) }' \
+    2>&5` || {
+  as_fn_error $? "confusing output from $NM -u" "$LINENO" 5
+}
+echo >&5 "libc_undefs='$libc_undefs'"
+case "$libc_undefs" in
+foobar) libc_cv_predef_stack_protector=no ;;
+'__stack_chk_fail
+foobar') libc_cv_predef_stack_protector=yes ;;
+*) as_fn_error $? "unexpected symbols in test: $libc_undefs" "$LINENO" 5 ;;
+esac
+else
+  as_fn_error $? "test compilation failed" "$LINENO" 5
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_predef_stack_protector" >&5
+$as_echo "$libc_cv_predef_stack_protector" >&6; }
+libc_extra_cflags=
+if test $libc_cv_predef_stack_protector = yes; then
+  libc_extra_cflags=-fno-stack-protector
+fi
+
+
 ### End of automated tests.
 ### Now run sysdeps configure fragments.
 
diff --git a/configure.in b/configure.in
index 0916e9ec5c..a9ee7334d6 100644
--- a/configure.in
+++ b/configure.in
@@ -927,6 +927,7 @@ AC_CHECK_PROG_VER(SED, sed, --version,
   SED=: aux_missing="$aux_missing sed")
 
 AC_CHECK_TOOL(READELF, readelf, false)
+AC_CHECK_TOOL(NM, nm, false)
 
 AC_CHECK_PROGS(AUTOCONF, autoconf, no)
 case "x$AUTOCONF" in
@@ -2052,6 +2053,39 @@ if test $libc_cv_predef_fortify_source = yes; then
 fi
 AC_SUBST(CPPUNDEFS)
 
+dnl Check for silly hacked compilers inserting -fstack-protector.
+dnl This breaks badly for the early startup code we compile, since
+dnl the compiled code can refer to a magic machine-dependent location
+dnl for the canary value before we have sufficient setup for that to
+dnl work.  It's also questionable to build all of libc with this flag
+dnl even when you're doing that for most applications you build, since
+dnl libc's code is so heavily-used and performance-sensitive.  If we
+dnl ever really want to make that work, it should be enabled explicitly
+dnl in the libc build, not inherited from implicit compiler settings.
+AC_CACHE_CHECK([whether $CC implicitly enables -fstack-protector],
+	       libc_cv_predef_stack_protector, [
+AC_TRY_COMPILE([extern void foobar (char *);],
+	       [char large_array[2048]; foobar (large_array);], [
+libc_undefs=`$NM -u conftest.o |
+  LC_ALL=C $AWK '$1 == "U" { print $2 | "sort -u"; next } { exit(1) }' \
+    2>&AS_MESSAGE_LOG_FD` || {
+  AC_MSG_ERROR([confusing output from $NM -u])
+}
+echo >&AS_MESSAGE_LOG_FD "libc_undefs='$libc_undefs'"
+case "$libc_undefs" in
+foobar) libc_cv_predef_stack_protector=no ;;
+'__stack_chk_fail
+foobar') libc_cv_predef_stack_protector=yes ;;
+*) AC_MSG_ERROR([unexpected symbols in test: $libc_undefs]) ;;
+esac],
+	       [AC_MSG_ERROR([test compilation failed])])
+])
+libc_extra_cflags=
+if test $libc_cv_predef_stack_protector = yes; then
+  libc_extra_cflags=-fno-stack-protector
+fi
+AC_SUBST(libc_extra_cflags)
+
 ### End of automated tests.
 ### Now run sysdeps configure fragments.