tools/patch/patches/010-CVE-2018-1000156.patch

   1 From ee2904728eb4364a36d62d66f723d0b68749e5df Mon Sep 17 00:00:00 2001
   2 From: Andreas Gruenbacher <agruen@gnu.org>
   3 Date: Fri, 6 Apr 2018 12:14:49 +0200
   4 Subject: [PATCH] Fix arbitrary command execution in ed-style patches
   5  (CVE-2018-1000156)
   6
   7 * src/pch.c (do_ed_script): Write ed script to a temporary file instead
   8 of piping it to ed: this will cause ed to abort on invalid commands
   9 instead of rejecting them and carrying on.
  10 * tests/ed-style: New test case.
  11 * tests/Makefile.am (TESTS): Add test case.
  12 ---
  13  src/pch.c         | 89 +++++++++++++++++++++++++++++++++++------------
  14  tests/Makefile.am |  1 +
  15  tests/ed-style    | 41 ++++++++++++++++++++++
  16  3 files changed, 108 insertions(+), 23 deletions(-)
  17  create mode 100644 tests/ed-style
  18
  19 diff --git a/src/pch.c b/src/pch.c
  20 index ff9ed2c..8150493 100644
  21 --- a/src/pch.c
  22 +++ b/src/pch.c
  23 @@ -33,6 +33,7 @@
  24  # include <io.h>
  25  #endif
  26  #include <safe.h>
  27 +#include <sys/wait.h>
  28
  29  #define INITHUNKMAX 125                        /* initial dynamic allocation size */
  30
  31 @@ -2388,22 +2389,28 @@ do_ed_script (char const *inname, char const *outname,
  32      static char const editor_program[] = EDITOR_PROGRAM;
  33
  34      file_offset beginning_of_this_line;
  35 -    FILE *pipefp = 0;
  36      size_t chars_read;
  37 +    FILE *tmpfp = 0;
  38 +    char const *tmpname;
  39 +    int tmpfd;
  40 +    pid_t pid;
  41 +
  42 +    if (! dry_run && ! skip_rest_of_patch)
  43 +      {
  44 +       /* Write ed script to a temporary file.  This causes ed to abort on
  45 +          invalid commands such as when line numbers or ranges exceed the
  46 +          number of available lines.  When ed reads from a pipe, it rejects
  47 +          invalid commands and treats the next line as a new command, which
  48 +          can lead to arbitrary command execution.  */
  49 +
  50 +       tmpfd = make_tempfile (&tmpname, 'e', NULL, O_RDWR | O_BINARY, 0);
  51 +       if (tmpfd == -1)
  52 +         pfatal ("Can't create temporary file %s", quotearg (tmpname));
  53 +       tmpfp = fdopen (tmpfd, "w+b");
  54 +       if (! tmpfp)
  55 +         pfatal ("Can't open stream for file %s", quotearg (tmpname));
  56 +      }
  57
  58 -    if (! dry_run && ! skip_rest_of_patch) {
  59 -       int exclusive = *outname_needs_removal ? 0 : O_EXCL;
  60 -       assert (! inerrno);
  61 -       *outname_needs_removal = true;
  62 -       copy_file (inname, outname, 0, exclusive, instat.st_mode, true);
  63 -       sprintf (buf, "%s %s%s", editor_program,
  64 -                verbosity == VERBOSE ? "" : "- ",
  65 -                outname);
  66 -       fflush (stdout);
  67 -       pipefp = popen(buf, binary_transput ? "wb" : "w");
  68 -       if (!pipefp)
  69 -         pfatal ("Can't open pipe to %s", quotearg (buf));
  70 -    }
  71      for (;;) {
  72         char ed_command_letter;
  73         beginning_of_this_line = file_tell (pfp);
  74 @@ -2414,14 +2421,14 @@ do_ed_script (char const *inname, char const *outname,
  75         }
  76         ed_command_letter = get_ed_command_letter (buf);
  77         if (ed_command_letter) {
  78 -           if (pipefp)
  79 -               if (! fwrite (buf, sizeof *buf, chars_read, pipefp))
  80 +           if (tmpfp)
  81 +               if (! fwrite (buf, sizeof *buf, chars_read, tmpfp))
  82                     write_fatal ();
  83             if (ed_command_letter != 'd' && ed_command_letter != 's') {
  84                 p_pass_comments_through = true;
  85                 while ((chars_read = get_line ()) != 0) {
  86 -                   if (pipefp)
  87 -                       if (! fwrite (buf, sizeof *buf, chars_read, pipefp))
  88 +                   if (tmpfp)
  89 +                       if (! fwrite (buf, sizeof *buf, chars_read, tmpfp))
  90                             write_fatal ();
  91                     if (chars_read == 2  &&  strEQ (buf, ".\n"))
  92                         break;
  93 @@ -2434,13 +2441,49 @@ do_ed_script (char const *inname, char const *outname,
  94             break;
  95         }
  96      }
  97 -    if (!pipefp)
  98 +    if (!tmpfp)
  99        return;
 100 -    if (fwrite ("w\nq\n", sizeof (char), (size_t) 4, pipefp) == 0
 101 -       || fflush (pipefp) != 0)
 102 +    if (fwrite ("w\nq\n", sizeof (char), (size_t) 4, tmpfp) == 0
 103 +       || fflush (tmpfp) != 0)
 104        write_fatal ();
 105 -    if (pclose (pipefp) != 0)
 106 -      fatal ("%s FAILED", editor_program);
 107 +
 108 +    if (lseek (tmpfd, 0, SEEK_SET) == -1)
 109 +      pfatal ("Can't rewind to the beginning of file %s", quotearg (tmpname));
 110 +
 111 +    if (! dry_run && ! skip_rest_of_patch) {
 112 +       int exclusive = *outname_needs_removal ? 0 : O_EXCL;
 113 +       *outname_needs_removal = true;
 114 +       if (inerrno != ENOENT)
 115 +         {
 116 +           *outname_needs_removal = true;
 117 +           copy_file (inname, outname, 0, exclusive, instat.st_mode, true);
 118 +         }
 119 +       sprintf (buf, "%s %s%s", editor_program,
 120 +                verbosity == VERBOSE ? "" : "- ",
 121 +                outname);
 122 +       fflush (stdout);
 123 +
 124 +       pid = fork();
 125 +       if (pid == -1)
 126 +         pfatal ("Can't fork");
 127 +       else if (pid == 0)
 128 +         {
 129 +           dup2 (tmpfd, 0);
 130 +           execl ("/bin/sh", "sh", "-c", buf, (char *) 0);
 131 +           _exit (2);
 132 +         }
 133 +       else
 134 +         {
 135 +           int wstatus;
 136 +           if (waitpid (pid, &wstatus, 0) == -1
 137 +               || ! WIFEXITED (wstatus)
 138 +               || WEXITSTATUS (wstatus) != 0)
 139 +             fatal ("%s FAILED", editor_program);
 140 +         }
 141 +    }
 142 +
 143 +    fclose (tmpfp);
 144 +    safe_unlink (tmpname);
 145
 146      if (ofp)
 147        {
 148 diff --git a/tests/Makefile.am b/tests/Makefile.am
 149 index 6b6df63..16f8693 100644
 150 --- a/tests/Makefile.am
 151 +++ b/tests/Makefile.am
 152 @@ -32,6 +32,7 @@ TESTS = \
 153         crlf-handling \
 154         dash-o-append \
 155         deep-directories \
 156 +       ed-style \
 157         empty-files \
 158         false-match \
 159         fifo \
 160 diff --git a/tests/ed-style b/tests/ed-style
 161 new file mode 100644
 162 index 0000000..d8c0689
 163 --- /dev/null
 164 +++ b/tests/ed-style
 165 @@ -0,0 +1,41 @@
 166 +# Copyright (C) 2018 Free Software Foundation, Inc.
 167 +#
 168 +# Copying and distribution of this file, with or without modification,
 169 +# in any medium, are permitted without royalty provided the copyright
 170 +# notice and this notice are preserved.
 171 +
 172 +. $srcdir/test-lib.sh
 173 +
 174 +require cat
 175 +use_local_patch
 176 +use_tmpdir
 177 +
 178 +# ==============================================================
 179 +
 180 +cat > ed1.diff <<EOF
 181 +0a
 182 +foo
 183 +.
 184 +EOF
 185 +
 186 +check 'patch -e foo -i ed1.diff' <<EOF
 187 +EOF
 188 +
 189 +check 'cat foo' <<EOF
 190 +foo
 191 +EOF
 192 +
 193 +cat > ed2.diff <<EOF
 194 +1337a
 195 +r !echo bar
 196 +,p
 197 +EOF
 198 +
 199 +check 'patch -e foo -i ed2.diff 2> /dev/null || echo "Status: $?"' <<EOF
 200 +?
 201 +Status: 2
 202 +EOF
 203 +
 204 +check 'cat foo' <<EOF
 205 +foo
 206 +EOF
 207 --
 208 2.19.1
 209