Re: [patch/rfc] handle GNU stack markings

[Paul Eggert]

Mike Frysinger <address@hidden> writes:

> some people see if the toolchain supports -Wa,--noexecstack while 

That's what glibc does, and that seems reasonable to me.

Thanks for mentioning this issue; it seems a good way to catch bugs of
a troublesome class.  I installed the following patch.

2006-12-08  Paul Eggert  <address@hidden>

        * configure.ac (for assembler): Set ASFLAGS_config to
        -Wa,--noexecstack if this seems advisable on this platform.
        Problem reported by Mike Frysinger in
        <http://lists.gnu.org/archive/html/bug-gzip/2006-12/msg00018.html>.
        * lib/Makefile.am (match.$(OBJEXT)): Use ASFLAGS_config.

Index: configure.ac
===================================================================
RCS file: /cvsroot/gzip/gzip/configure.ac,v
retrieving revision 1.7
diff -p -u -r1.7 configure.ac
--- configure.ac        8 Dec 2006 00:20:33 -0000       1.7
+++ configure.ac        8 Dec 2006 09:29:01 -0000
@@ -64,16 +64,30 @@ AC_CACHE_CHECK([for assembler], [gzip_cv
         :
        elif eval "$CC -c match_.s >/dev/null 2>&1" &&
            test -f match_.$OBJEXT; then
+        rm -f match_.$OBJEXT
         gzip_cv_assembler=yes
+        if echo 'void foo (void) {}' > conftest.c &&
+           eval "$CC -S conftest.c >/dev/null 2>&1" &&
+           grep '\.note\.GNU-stack' conftest.s >/dev/null 2>&1 &&
+           eval "$CC -c -Wa,--noexecstack match_.s >/dev/null 2>&1" &&
+           test -f match_.$OBJEXT; then
+          gzip_cv_assembler='yes, with -Wa,--noexecstack'
+        fi
        fi
      fi
-     rm -f _match.S match_.s match_.$OBJEXT;;
+     rm -f conftest* _match.S match_.s match_.$OBJEXT;;
    esac])
-if test $gzip_cv_assembler = yes; then
+if test "$gzip_cv_assembler" != no; then
   AC_DEFINE(ASMV, ,
     [Define if an assembler version of longest_match is available.])
   AC_LIBOBJ(match)
 fi
+if test "$gzip_cv_assembler" = 'yes, with -Wa,--noexecstack'; then
+  ASFLAGS_config='-Wa,--noexecstack'
+else
+  ASFLAGS_config=
+fi
+AC_SUBST([ASFLAGS_config])
 
 AC_ISC_POSIX
 AC_C_CONST
Index: lib/Makefile.am
===================================================================
RCS file: /cvsroot/gzip/gzip/lib/Makefile.am,v
retrieving revision 1.2
diff -p -u -r1.2 Makefile.am
--- lib/Makefile.am     7 Dec 2006 07:23:35 -0000       1.2
+++ lib/Makefile.am     8 Dec 2006 09:29:01 -0000
@@ -28,7 +28,7 @@ LN_S = @LN_S@
 match.$(OBJEXT): match.c
        cp $(srcdir)/match.c _match.S
        $(ASCPP) _match.S > match_.s
-       $(CC) -c $(CFLAGS) match_.s
+       $(CC) -c $(CFLAGS) $(ASFLAGS_config) match_.s
        mv match_.$(OBJEXT) $@
        rm -f _match.S match_.s