ptx: avoid heap overrun for backslash at end of optarg string

* src/ptx.c (copy_unescaped_string): Ignore a lone backslash
at end of string.  Reported by Cristian Cadar, Daniel Dunbar
and Dawson Engler.  Details here:
<http://thread.gmane.org/gmane.comp.gnu.coreutils.bugs/13005>.
* tests/misc/Makefile.am (TESTS): Add ptx-overrun.
* tests/misc/ptx-overrun: New file.  Test for the above fix.
* NEWS: Mention the fix.

Signed-off-by: Jim Meyering <meyering@redhat.com>

NEWS

@@ -16,6 +16,11 @@ GNU coreutils NEWS                                    -*- outline -*-
   when the destination had two or more hard links.  It no longer does that.
   [bug introduced in coreutils-5.3.0]
 
+  "ptx -F'\' long-file-name" would overrun a malloc'd buffer and corrupt
+  the heap.  That was triggered by a lone backslash (or odd number of them)
+  at the end of the option argument to --flag-truncation=STRING (-F),
+  --word-regexp=REGEXP (-W), or --sentence-regexp=REGEXP (-S).
+
   "rmdir --ignore-fail-on-non-empty" detects and ignores the failure
   in more cases when a directory is empty.
 

THANKS

@@ -105,12 +105,14 @@ Colin Plumb                         colin@nyx.net
 Colin Watson                        cjw44@riva.ucam.org
 Collin Rogowski                     collin@rogowski.de
 Cray-Cyber Project                  http://www.cray-cyber.org
+Cristian Cadar                      cristic@stanford.edu
 Cyril Bouthors                      cyril@bouthors.org
 Dale Scheetz                        dwarf@polaris.net
 Dan Hagerty                         hag@gnu.ai.it.edu
 Dan Jacobson                        http://www.geocities.com/jidani
 Dan Pascu                           dan@services.iiruc.ro
 Daniel Bergstrom                    noa@melody.se
+Daniel Dunbar                       ddunbar@stanford.edu
 Daniel P. Berrangé                  berrange@redhat.com
 Dániel Varga                        danielv@axelero.hu
 Danny Levinson                      danny.levinson@overture.com
@@ -125,6 +127,7 @@ David Godfrey                       dave@delta.demon.co.uk
 David Luyer                         david_luyer@pacific.net.au
 David Madore                        david.madore@ens.fr
 David Malone                        dwmalone@cnri.dit.ie
+Dawson Engler                       engler@stanford.edu
 Dean Gaudet                         dean-savannah@arctic.org
 Deepak Goel                         deego@gnufans.org
 Dennis Henriksen                    opus@flamingo.osrl.dk

src/ptx.c

@@ -388,6 +388,10 @@ copy_unescaped_string (const char *string)
 	      string++;
 	      break;
 
+	    case '\0':		/* lone backslash at end of string */
+	      /* ignore it */
+	      break;
+
 	    default:
 	      *cursor++ = '\\';
 	      *cursor++ = *string++;

tests/misc/Makefile.am

@@ -1,6 +1,6 @@
 # Make miscellaneous coreutils tests.			-*-Makefile-*-
 
-# Copyright (C) 2001-2007 Free Software Foundation, Inc.
+# Copyright (C) 2001-2008 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
@@ -38,6 +38,7 @@ TESTS = \
   ls-time \
   ls-misc \
   date \
+  ptx-overrun \
   xstrtol \
   od \
   mktemp \

tests/misc/ptx-overrun

@@ -0,0 +1,40 @@
+#!/bin/sh
+# Trigger a heap-clobbering bug in ptx from coreutils-6.10 and earlier.
+
+# Copyright (C) 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/>.
+
+if test "$VERBOSE" = yes; then
+  set -x
+  ptx --version
+fi
+
+. $srcdir/../test-lib.sh
+
+# Using a long file name makes an abort more likely.
+# Even with no file name, valgrind detects the buffer overrun.
+f=01234567890123456789012345678901234567890123456789
+touch $f empty || framework_failure
+
+fail=0
+
+# Specifying a regular expression ending in a lone backslash
+# would cause ptx to write beyond the end of a malloc'd buffer.
+ptx -F '\'      $f < /dev/null  > out || fail=1
+ptx -S 'foo\'   $f < /dev/null >> out || fail=1
+ptx -W 'bar\\\' $f < /dev/null >> out || fail=1
+compare out empty || fail=1
+
+(exit $fail); exit $fail