gdb/

* NEWS (New commands): Mention "set disable-randomization".
	* configure.ac: Add check for HAVE_PERSONALITY and
	HAVE_DECL_ADDR_NO_RANDOMIZE.
	* configure, config.in: Regenerate.
	* linux-nat.c [HAVE_PERSONALITY]: New include <sys/personality.h>.
	[HAVE_PERSONALITY] [!HAVE_DECL_ADDR_NO_RANDOMIZE]: Set
	ADDR_NO_RANDOMIZE.
	(disable_randomization, show_disable_randomization)
	(set_disable_randomization): New.
	(linux_nat_create_inferior) [HAVE_PERSONALITY]: New variables
	PERSONALITY_ORIG and PERSONALITY_SET.  Disable randomization upon the
	variable DISABLE_RANDOMIZATION.
	(_initialize_linux_nat): Call ADD_SETSHOW_BOOLEAN_CMD for the variable
	DISABLE_RANDOMIZATION.

gdb/doc/
	* gdb.texinfo (Starting): Document "set disable-randomization".

gdb/testsuite/
	* gdb.base/randomize.exp, gdb.base/randomize.c: New files.

gdb/ChangeLog

@@ -1,3 +1,20 @@
+2008-07-10  Jan Kratochvil  <jan.kratochvil@redhat.com>
+
+	* NEWS (New commands): Mention "set disable-randomization".
+	* configure.ac: Add check for HAVE_PERSONALITY and
+	HAVE_DECL_ADDR_NO_RANDOMIZE.
+	* configure, config.in: Regenerate.
+	* linux-nat.c [HAVE_PERSONALITY]: New include <sys/personality.h>.
+	[HAVE_PERSONALITY] [!HAVE_DECL_ADDR_NO_RANDOMIZE]: Set
+	ADDR_NO_RANDOMIZE.
+	(disable_randomization, show_disable_randomization)
+	(set_disable_randomization): New.
+	(linux_nat_create_inferior) [HAVE_PERSONALITY]: New variables
+	PERSONALITY_ORIG and PERSONALITY_SET.  Disable randomization upon the
+	variable DISABLE_RANDOMIZATION.
+	(_initialize_linux_nat): Call ADD_SETSHOW_BOOLEAN_CMD for the variable
+	DISABLE_RANDOMIZATION.
+
 2008-07-09  Pedro Alves  <pedro@codesourcery.com>
 
 	Adjust all targets to new target_stop interface.

gdb/NEWS

@@ -98,6 +98,12 @@ show arm force-mode
   the current CPSR value for instructions without symbols; previous
   versions of GDB behaved as if "set arm fallback-mode arm".
 
+set disable-randomization
+show disable-randomization
+  Standalone programs run with the virtual address space randomization enabled
+  by default on some platforms.  This option keeps the addresses stable across
+  multiple debugging sessions.
+
 * New targets
 
 x86 DICOS			i[34567]86-*-dicos*

gdb/config.in

@@ -82,6 +82,10 @@
 /* Define to 1 if you have the <curses.h> header file. */
 #undef HAVE_CURSES_H
 
+/* Define to 1 if you have the declaration of `ADDR_NO_RANDOMIZE', and to 0 if
+   you don't. */
+#undef HAVE_DECL_ADDR_NO_RANDOMIZE
+
 /* Define to 1 if you have the declaration of `free', and to 0 if you don't.
    */
 #undef HAVE_DECL_FREE
@@ -237,6 +241,9 @@
 /* Define to 1 if you have the <nlist.h> header file. */
 #undef HAVE_NLIST_H
 
+/* Define if you support the personality syscall. */
+#undef HAVE_PERSONALITY
+
 /* Define to 1 if you have the `poll' function. */
 #undef HAVE_POLL
 

gdb/configure

@@ -23669,6 +23669,188 @@ _ACEOF
 
 fi
 
+echo "$as_me:$LINENO: checking whether ADDR_NO_RANDOMIZE is declared" >&5
+echo $ECHO_N "checking whether ADDR_NO_RANDOMIZE is declared... $ECHO_C" >&6
+if test "${ac_cv_have_decl_ADDR_NO_RANDOMIZE+set}" = set; then
+  echo $ECHO_N "(cached) $ECHO_C" >&6
+else
+  cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+#include <sys/personality.h>
+
+int
+main ()
+{
+#ifndef ADDR_NO_RANDOMIZE
+  char *p = (char *) ADDR_NO_RANDOMIZE;
+#endif
+
+  ;
+  return 0;
+}
+_ACEOF
+rm -f conftest.$ac_objext
+if { (eval echo "$as_me:$LINENO: \"$ac_compile\"") >&5
+  (eval $ac_compile) 2>conftest.er1
+  ac_status=$?
+  grep -v '^ *+' conftest.er1 >conftest.err
+  rm -f conftest.er1
+  cat conftest.err >&5
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } &&
+	 { ac_try='test -z "$ac_c_werror_flag"
+			 || test ! -s conftest.err'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; } &&
+	 { ac_try='test -s conftest.$ac_objext'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; }; then
+  ac_cv_have_decl_ADDR_NO_RANDOMIZE=yes
+else
+  echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+ac_cv_have_decl_ADDR_NO_RANDOMIZE=no
+fi
+rm -f conftest.err conftest.$ac_objext conftest.$ac_ext
+fi
+echo "$as_me:$LINENO: result: $ac_cv_have_decl_ADDR_NO_RANDOMIZE" >&5
+echo "${ECHO_T}$ac_cv_have_decl_ADDR_NO_RANDOMIZE" >&6
+if test $ac_cv_have_decl_ADDR_NO_RANDOMIZE = yes; then
+
+cat >>confdefs.h <<_ACEOF
+#define HAVE_DECL_ADDR_NO_RANDOMIZE 1
+_ACEOF
+
+
+else
+  cat >>confdefs.h <<_ACEOF
+#define HAVE_DECL_ADDR_NO_RANDOMIZE 0
+_ACEOF
+
+
+fi
+
+
+
+if test "$cross_compiling" = yes; then
+  cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+#include <sys/personality.h>
+int
+main ()
+{
+
+#      if !HAVE_DECL_ADDR_NO_RANDOMIZE
+#       define ADDR_NO_RANDOMIZE 0x0040000
+#      endif
+       /* Test the flag could be set and stays set.  */
+       personality (personality (0xffffffff) | ADDR_NO_RANDOMIZE);
+       if (!(personality (personality (0xffffffff)) & ADDR_NO_RANDOMIZE))
+	   return 1
+  ;
+  return 0;
+}
+_ACEOF
+rm -f conftest.$ac_objext conftest$ac_exeext
+if { (eval echo "$as_me:$LINENO: \"$ac_link\"") >&5
+  (eval $ac_link) 2>conftest.er1
+  ac_status=$?
+  grep -v '^ *+' conftest.er1 >conftest.err
+  rm -f conftest.er1
+  cat conftest.err >&5
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } &&
+	 { ac_try='test -z "$ac_c_werror_flag"
+			 || test ! -s conftest.err'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; } &&
+	 { ac_try='test -s conftest$ac_exeext'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; }; then
+  have_personality=true
+else
+  echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+have_personality=false
+fi
+rm -f conftest.err conftest.$ac_objext \
+      conftest$ac_exeext conftest.$ac_ext
+else
+  cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+#include <sys/personality.h>
+int
+main ()
+{
+
+#      if !HAVE_DECL_ADDR_NO_RANDOMIZE
+#       define ADDR_NO_RANDOMIZE 0x0040000
+#      endif
+       /* Test the flag could be set and stays set.  */
+       personality (personality (0xffffffff) | ADDR_NO_RANDOMIZE);
+       if (!(personality (personality (0xffffffff)) & ADDR_NO_RANDOMIZE))
+	   return 1
+  ;
+  return 0;
+}
+_ACEOF
+rm -f conftest$ac_exeext
+if { (eval echo "$as_me:$LINENO: \"$ac_link\"") >&5
+  (eval $ac_link) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } && { ac_try='./conftest$ac_exeext'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; }; then
+  have_personality=true
+else
+  echo "$as_me: program exited with status $ac_status" >&5
+echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+( exit $ac_status )
+have_personality=false
+fi
+rm -f core *.core gmon.out bb.out conftest$ac_exeext conftest.$ac_objext conftest.$ac_ext
+fi
+if $have_personality
+then
+
+cat >>confdefs.h <<\_ACEOF
+#define HAVE_PERSONALITY 1
+_ACEOF
+
+fi
+
 
 
 # Check whether --with-sysroot or --without-sysroot was given.

gdb/configure.ac

@@ -1268,6 +1268,29 @@ if test "x$gdb_cv_sys_syscall_h_has_tkill" = "xyes" && test "x$ac_cv_func_syscal
   AC_DEFINE(HAVE_TKILL_SYSCALL, 1, [Define if you support the tkill syscall.])
 fi
 
+dnl Check if we can disable the virtual address space randomization.
+dnl The functionality of setarch -R.
+AC_CHECK_DECLS([ADDR_NO_RANDOMIZE],,, [#include <sys/personality.h>])
+define([PERSONALITY_TEST], [AC_LANG_PROGRAM([#include <sys/personality.h>], [
+#      if !HAVE_DECL_ADDR_NO_RANDOMIZE
+#       define ADDR_NO_RANDOMIZE 0x0040000
+#      endif
+       /* Test the flag could be set and stays set.  */
+       personality (personality (0xffffffff) | ADDR_NO_RANDOMIZE);
+       if (!(personality (personality (0xffffffff)) & ADDR_NO_RANDOMIZE))
+	   return 1])])
+AC_RUN_IFELSE([PERSONALITY_TEST],
+	      [have_personality=true],
+	      [have_personality=false],
+	      [AC_LINK_IFELSE([PERSONALITY_TEST],
+			      [have_personality=true],
+			      [have_personality=false])])
+if $have_personality
+then
+    AC_DEFINE([HAVE_PERSONALITY], 1,
+	      [Define if you support the personality syscall.])
+fi
+
 dnl Handle optional features that can be enabled.
 
 AC_ARG_WITH(sysroot,

gdb/doc/ChangeLog

@@ -1,3 +1,7 @@
+2008-07-10  Jan Kratochvil  <jan.kratochvil@redhat.com>
+
+	* gdb.texinfo (Starting): Document "set disable-randomization".
+
 2008-07-07  Andreas Schwab  <schwab@suse.de>
 
 	* gdb.texinfo (GDB/MI Target Manipulation): Fix last change.

gdb/doc/gdb.texinfo

@@ -1999,6 +1999,57 @@ environment:
 This command is available when debugging locally on most targets, excluding
 @sc{djgpp}, Cygwin, MS Windows, and QNX Neutrino.
 
+@kindex set disable-randomization
+@item set disable-randomization
+@itemx set disable-randomization on
+This option (enabled by default in @value{GDBN}) will turn off the native
+randomization of the virtual address space of the started program.  This option
+is useful for multiple debugging sessions to make the execution better
+reproducible and memory addresses reusable across debugging sessions.
+
+This feature is implemented only on @sc{gnu}/Linux.  You can get the same
+behavior using
+
+@smallexample
+(@value{GDBP}) set exec-wrapper setarch `uname -m` -R
+@end smallexample
+
+@item set disable-randomization off
+Leave the behavior of the started executable unchanged.  Some bugs rear their
+ugly heads only when the program is loaded at certain addresses.  If your bug
+disappears when you run the program under @value{GDBN}, that might be because
+@value{GDBN} by default disables the address randomization on platforms, such
+as @sc{gnu}/Linux, which do that for stand-alone programs.  Use @kbd{set
+disable-randomization off} to try to reproduce such elusive bugs.
+
+The virtual address space randomization is implemented only on @sc{gnu}/Linux.
+It protects the programs against some kinds of security attacks.  In these
+cases the attacker needs to know the exact location of a concrete executable
+code.  Randomizing its location makes it impossible to inject jumps misusing
+a code at its expected addresses.
+
+Prelinking shared libraries provides a startup performance advantage but it
+makes addresses in these libraries predictable for privileged processes by
+having just unprivileged access at the target system.  Reading the shared
+library binary gives enough information for assembling the malicious code
+misusing it.  Still even a prelinked shared library can get loaded at a new
+random address just requiring the regular relocation process during the
+startup.  Shared libraries not already prelinked are always loaded at
+a randomly chosen address.
+
+Position independent executables (PIE) contain position independent code
+similar to the shared libraries and therefore such executables get loaded at
+a randomly chosen address upon startup.  PIE executables always load even
+already prelinked shared libraries at a random address.  You can build such
+executable using @command{gcc -fPIE -pie}.
+
+Heap (malloc storage), stack and custom mmap areas are always placed randomly
+(as long as the randomization is enabled).
+
+@item show disable-randomization
+Show the current setting of the explicit disable of the native randomization of
+the virtual address space of the started program.
+
 @end table
 
 @node Arguments

gdb/linux-nat.c

@@ -50,6 +50,13 @@
 #include "event-loop.h"
 #include "event-top.h"
 
+#ifdef HAVE_PERSONALITY
+# include <sys/personality.h>
+# if !HAVE_DECL_ADDR_NO_RANDOMIZE
+#  define ADDR_NO_RANDOMIZE 0x0040000
+# endif
+#endif /* HAVE_PERSONALITY */
+
 /* This comment documents high-level logic of this file. 
 
 Waiting for events in sync mode
@@ -220,6 +227,33 @@ show_debug_linux_nat_async (struct ui_file *file, int from_tty,
 		    value);
 }
 
+static int disable_randomization = 1;
+
+static void
+show_disable_randomization (struct ui_file *file, int from_tty,
+			    struct cmd_list_element *c, const char *value)
+{
+#ifdef HAVE_PERSONALITY
+  fprintf_filtered (file, _("\
+Disabling randomization of debuggee's virtual address space is %s.\n"),
+		    value);
+#else /* !HAVE_PERSONALITY */
+  fputs_filtered (_("\
+Disabling randomization of debuggee's virtual address space is unsupported on\n\
+this platform.\n"), file);
+#endif /* !HAVE_PERSONALITY */
+}
+
+static void
+set_disable_randomization (char *args, int from_tty, struct cmd_list_element *c)
+{
+#ifndef HAVE_PERSONALITY
+  error (_("\
+Disabling randomization of debuggee's virtual address space is unsupported on\n\
+this platform."));
+#endif /* !HAVE_PERSONALITY */
+}
+
 static int linux_parent_pid;
 
 struct simple_pid_list
@@ -1279,6 +1313,9 @@ linux_nat_create_inferior (char *exec_file, char *allargs, char **env,
 			   int from_tty)
 {
   int saved_async = 0;
+#ifdef HAVE_PERSONALITY
+  int personality_orig = 0, personality_set = 0;
+#endif /* HAVE_PERSONALITY */
 
   /* The fork_child mechanism is synchronous and calls target_wait, so
      we have to mask the async mode.  */
@@ -1302,8 +1339,36 @@ linux_nat_create_inferior (char *exec_file, char *allargs, char **env,
      the inferior execing.  */
   linux_nat_async_events (sigchld_default);
 
+#ifdef HAVE_PERSONALITY
+  if (disable_randomization)
+    {
+      errno = 0;
+      personality_orig = personality (0xffffffff);
+      if (errno == 0 && !(personality_orig & ADDR_NO_RANDOMIZE))
+	{
+	  personality_set = 1;
+	  personality (personality_orig | ADDR_NO_RANDOMIZE);
+	}
+      if (errno != 0 || (personality_set
+			 && !(personality (0xffffffff) & ADDR_NO_RANDOMIZE)))
+	warning (_("Error disabling address space randomization: %s"),
+		 safe_strerror (errno));
+    }
+#endif /* HAVE_PERSONALITY */
+
   linux_ops->to_create_inferior (exec_file, allargs, env, from_tty);
 
+#ifdef HAVE_PERSONALITY
+  if (personality_set)
+    {
+      errno = 0;
+      personality (personality_orig);
+      if (errno != 0)
+	warning (_("Error restoring address space randomization: %s"),
+		 safe_strerror (errno));
+    }
+#endif /* HAVE_PERSONALITY */
+
   if (saved_async)
     linux_nat_async_mask (saved_async);
 }
@@ -4378,6 +4443,17 @@ Tells gdb whether to control the GNU/Linux inferior in asynchronous mode."),
 
   /* Install the default mode.  */
   linux_nat_set_async_mode (linux_async_permitted);
+
+  add_setshow_boolean_cmd ("disable-randomization", class_support,
+			   &disable_randomization, _("\
+Set disabling of debuggee's virtual address space randomization."), _("\
+Show disabling of debuggee's virtual address space randomization."), _("\
+When this mode is on (which is the default), randomization of the virtual\n\
+address space is disabled.  Standalone programs run with the randomization\n\
+enabled by default on some platforms."),
+			   &set_disable_randomization,
+			   &show_disable_randomization,
+			   &setlist, &showlist);
 }
 
 

gdb/testsuite/ChangeLog

@@ -1,3 +1,7 @@
+2008-07-10  Jan Kratochvil  <jan.kratochvil@redhat.com>
+
+	* gdb.base/randomize.exp, gdb.base/randomize.c: New files.
+
 2008-07-09  Pedro Alves  <pedro@codesourcery.com>
 
 	* gdb.base/chng-syms.exp: Don't expect "No symbol ...".

gdb/testsuite/gdb.base/randomize.c

@@ -0,0 +1,31 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2008 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+   Please email any bugs, comments, and/or additions to this file to:
+   bug-gdb@prep.ai.mit.edu  */
+
+#include <stdlib.h>
+#include <stdio.h>
+
+int main()
+{
+  void *p;
+
+  p = malloc (1);
+
+  return 0; /* print p */
+}

gdb/testsuite/gdb.base/randomize.exp

@@ -0,0 +1,87 @@
+# Copyright 2008 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+set testfile randomize
+set srcfile ${testfile}.c
+set binfile ${objdir}/${subdir}/${testfile}
+if  { [gdb_compile "${srcdir}/${subdir}/${srcfile}" "${binfile}" executable {debug}] != "" } {
+    untested "Couldn't compile test program"
+    return -1
+}
+
+# Get things started.
+
+gdb_exit
+gdb_start
+gdb_reinitialize_dir $srcdir/$subdir
+gdb_load ${binfile}
+
+proc address_get { testname } {
+    global gdb_prompt
+
+    if {![runto_main]} {
+	return -1
+    }
+
+    # Do not rely on printf; some test configurations don't work with stdio.
+
+    gdb_breakpoint [gdb_get_line_number "print p"]
+    gdb_continue_to_breakpoint "$testname - address set"
+
+    gdb_test_multiple "print/x p" $testname {
+	-re "\\$\[0-9\]+ = (0x\[0-9a-f\]*)\r?\n$gdb_prompt $" {
+	    pass $testname
+	    return $expect_out(1,string)
+	}
+    }
+}
+
+set test "set disable-randomization off"
+gdb_test_multiple "${test}" "${test}" {
+    -re "Disabling randomization .* unsupported .*$gdb_prompt $" {
+	untested "No randomization supported by this GDB"
+	return -1
+    }
+    -re "$gdb_prompt $" {
+	pass $test
+    }
+}
+gdb_test "show disable-randomization"	      \
+         "Disabling randomization .* is off." \
+         "show disable-randomization off"
+
+set addr1 [address_get "randomized first address"]
+set addr2 [address_get "randomized second address"]
+set test "randomized addresses should not match"
+if {$addr1 eq $addr2} {
+    untested "No randomization detected on this system"
+    return -1
+} else {
+    pass $test
+}
+
+gdb_test "set disable-randomization on"
+gdb_test "show disable-randomization"	      \
+         "Disabling randomization .* is on." \
+         "show disable-randomization on"
+
+set addr1 [address_get "fixed first address"]
+set addr2 [address_get "fixed second address"]
+set test "fixed addresses should match"
+if {$addr1 eq $addr2} {
+    pass $test
+} else {
+    fail $test
+}