patches/patch/Fix_arbitrary_command_execution_in_ed-style_patches.patch

   1 From 123eaff0d5d1aebe128295959435b9ca5909c26d 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: 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         | 91 ++++++++++++++++++++++++++++++++++++++++---------------
  14  tests/Makefile.am |  1 +
  15  tests/ed-style    | 41 +++++++++++++++++++++++++
  16  3 files changed, 108 insertions(+), 25 deletions(-)
  17  create mode 100644 tests/ed-style
  18
  19 diff --git a/src/pch.c b/src/pch.c
  20 index 0c5cc26..4fd5a05 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 @@ -2389,24 +2390,28 @@ 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 -       if (inerrno != ENOENT)
  61 -         {
  62 -           *outname_needs_removal = true;
  63 -           copy_file (inname, outname, 0, exclusive, instat.st_mode, true);
  64 -         }
  65 -       sprintf (buf, "%s %s%s", editor_program,
  66 -                verbosity == VERBOSE ? "" : "- ",
  67 -                outname);
  68 -       fflush (stdout);
  69 -       pipefp = popen(buf, binary_transput ? "wb" : "w");
  70 -       if (!pipefp)
  71 -         pfatal ("Can't open pipe to %s", quotearg (buf));
  72 -    }
  73      for (;;) {
  74         char ed_command_letter;
  75         beginning_of_this_line = file_tell (pfp);
  76 @@ -2417,14 +2422,14 @@ do_ed_script (char const *inname, char const *outname,
  77         }
  78         ed_command_letter = get_ed_command_letter (buf);
  79         if (ed_command_letter) {
  80 -           if (pipefp)
  81 -               if (! fwrite (buf, sizeof *buf, chars_read, pipefp))
  82 +           if (tmpfp)
  83 +               if (! fwrite (buf, sizeof *buf, chars_read, tmpfp))
  84                     write_fatal ();
  85             if (ed_command_letter != 'd' && ed_command_letter != 's') {
  86                 p_pass_comments_through = true;
  87                 while ((chars_read = get_line ()) != 0) {
  88 -                   if (pipefp)
  89 -                       if (! fwrite (buf, sizeof *buf, chars_read, pipefp))
  90 +                   if (tmpfp)
  91 +                       if (! fwrite (buf, sizeof *buf, chars_read, tmpfp))
  92                             write_fatal ();
  93                     if (chars_read == 2  &&  strEQ (buf, ".\n"))
  94                         break;
  95 @@ -2437,13 +2442,49 @@ do_ed_script (char const *inname, char const *outname,
  96             break;
  97         }
  98      }
  99 -    if (!pipefp)
 100 +    if (!tmpfp)
 101        return;
 102 -    if (fwrite ("w\nq\n", sizeof (char), (size_t) 4, pipefp) == 0
 103 -       || fflush (pipefp) != 0)
 104 +    if (fwrite ("w\nq\n", sizeof (char), (size_t) 4, tmpfp) == 0
 105 +       || fflush (tmpfp) != 0)
 106        write_fatal ();
 107 -    if (pclose (pipefp) != 0)
 108 -      fatal ("%s FAILED", editor_program);
 109 +
 110 +    if (lseek (tmpfd, 0, SEEK_SET) == -1)
 111 +      pfatal ("Can't rewind to the beginning of file %s", quotearg (tmpname));
 112 +
 113 +    if (! dry_run && ! skip_rest_of_patch) {
 114 +       int exclusive = *outname_needs_removal ? 0 : O_EXCL;
 115 +       *outname_needs_removal = true;
 116 +       if (inerrno != ENOENT)
 117 +         {
 118 +           *outname_needs_removal = true;
 119 +           copy_file (inname, outname, 0, exclusive, instat.st_mode, true);
 120 +         }
 121 +       sprintf (buf, "%s %s%s", editor_program,
 122 +                verbosity == VERBOSE ? "" : "- ",
 123 +                outname);
 124 +       fflush (stdout);
 125 +
 126 +       pid = fork();
 127 +       if (pid == -1)
 128 +         pfatal ("Can't fork");
 129 +       else if (pid == 0)
 130 +         {
 131 +           dup2 (tmpfd, 0);
 132 +           execl ("/bin/sh", "sh", "-c", buf, (char *) 0);
 133 +           _exit (2);
 134 +         }
 135 +       else
 136 +         {
 137 +           int wstatus;
 138 +           if (waitpid (pid, &wstatus, 0) == -1
 139 +               || ! WIFEXITED (wstatus)
 140 +               || WEXITSTATUS (wstatus) != 0)
 141 +             fatal ("%s FAILED", editor_program);
 142 +         }
 143 +    }
 144 +
 145 +    fclose (tmpfp);
 146 +    safe_unlink (tmpname);
 147
 148      if (ofp)
 149        {
 150 diff --git a/tests/Makefile.am b/tests/Makefile.am
 151 index 6b6df63..16f8693 100644
 152 --- a/tests/Makefile.am
 153 +++ b/tests/Makefile.am
 154 @@ -32,6 +32,7 @@ TESTS = \
 155         crlf-handling \
 156         dash-o-append \
 157         deep-directories \
 158 +       ed-style \
 159         empty-files \
 160         false-match \
 161         fifo \
 162 diff --git a/tests/ed-style b/tests/ed-style
 163 new file mode 100644
 164 index 0000000..d8c0689
 165 --- /dev/null
 166 +++ b/tests/ed-style
 167 @@ -0,0 +1,41 @@
 168 +# Copyright (C) 2018 Free Software Foundation, Inc.
 169 +#
 170 +# Copying and distribution of this file, with or without modification,
 171 +# in any medium, are permitted without royalty provided the copyright
 172 +# notice and this notice are preserved.
 173 +
 174 +. $srcdir/test-lib.sh
 175 +
 176 +require cat
 177 +use_local_patch
 178 +use_tmpdir
 179 +
 180 +# ==============================================================
 181 +
 182 +cat > ed1.diff <<EOF
 183 +0a
 184 +foo
 185 +.
 186 +EOF
 187 +
 188 +check 'patch -e foo -i ed1.diff' <<EOF
 189 +EOF
 190 +
 191 +check 'cat foo' <<EOF
 192 +foo
 193 +EOF
 194 +
 195 +cat > ed2.diff <<EOF
 196 +1337a
 197 +r !echo bar
 198 +,p
 199 +EOF
 200 +
 201 +check 'patch -e foo -i ed2.diff 2> /dev/null || echo "Status: $?"' <<EOF
 202 +?
 203 +Status: 2
 204 +EOF
 205 +
 206 +check 'cat foo' <<EOF
 207 +foo
 208 +EOF
 209 --
 210 cgit v1.0-41-gc330
 211