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 --- a/src/pch.c
  20 +++ b/src/pch.c
  21 @@ -33,6 +33,7 @@
  22  # include <io.h>
  23  #endif
  24  #include <safe.h>
  25 +#include <sys/wait.h>
  26
  27  #define INITHUNKMAX 125                        /* initial dynamic allocation size */
  28
  29 @@ -2388,22 +2389,28 @@ do_ed_script (char const *inname, char c
  30      static char const editor_program[] = EDITOR_PROGRAM;
  31
  32      file_offset beginning_of_this_line;
  33 -    FILE *pipefp = 0;
  34      size_t chars_read;
  35 +    FILE *tmpfp = 0;
  36 +    char const *tmpname;
  37 +    int tmpfd;
  38 +    pid_t pid;
  39 +
  40 +    if (! dry_run && ! skip_rest_of_patch)
  41 +      {
  42 +       /* Write ed script to a temporary file.  This causes ed to abort on
  43 +          invalid commands such as when line numbers or ranges exceed the
  44 +          number of available lines.  When ed reads from a pipe, it rejects
  45 +          invalid commands and treats the next line as a new command, which
  46 +          can lead to arbitrary command execution.  */
  47 +
  48 +       tmpfd = make_tempfile (&tmpname, 'e', NULL, O_RDWR | O_BINARY, 0);
  49 +       if (tmpfd == -1)
  50 +         pfatal ("Can't create temporary file %s", quotearg (tmpname));
  51 +       tmpfp = fdopen (tmpfd, "w+b");
  52 +       if (! tmpfp)
  53 +         pfatal ("Can't open stream for file %s", quotearg (tmpname));
  54 +      }
  55
  56 -    if (! dry_run && ! skip_rest_of_patch) {
  57 -       int exclusive = *outname_needs_removal ? 0 : O_EXCL;
  58 -       assert (! inerrno);
  59 -       *outname_needs_removal = true;
  60 -       copy_file (inname, outname, 0, exclusive, instat.st_mode, true);
  61 -       sprintf (buf, "%s %s%s", editor_program,
  62 -                verbosity == VERBOSE ? "" : "- ",
  63 -                outname);
  64 -       fflush (stdout);
  65 -       pipefp = popen(buf, binary_transput ? "wb" : "w");
  66 -       if (!pipefp)
  67 -         pfatal ("Can't open pipe to %s", quotearg (buf));
  68 -    }
  69      for (;;) {
  70         char ed_command_letter;
  71         beginning_of_this_line = file_tell (pfp);
  72 @@ -2414,14 +2421,14 @@ do_ed_script (char const *inname, char c
  73         }
  74         ed_command_letter = get_ed_command_letter (buf);
  75         if (ed_command_letter) {
  76 -           if (pipefp)
  77 -               if (! fwrite (buf, sizeof *buf, chars_read, pipefp))
  78 +           if (tmpfp)
  79 +               if (! fwrite (buf, sizeof *buf, chars_read, tmpfp))
  80                     write_fatal ();
  81             if (ed_command_letter != 'd' && ed_command_letter != 's') {
  82                 p_pass_comments_through = true;
  83                 while ((chars_read = get_line ()) != 0) {
  84 -                   if (pipefp)
  85 -                       if (! fwrite (buf, sizeof *buf, chars_read, pipefp))
  86 +                   if (tmpfp)
  87 +                       if (! fwrite (buf, sizeof *buf, chars_read, tmpfp))
  88                             write_fatal ();
  89                     if (chars_read == 2  &&  strEQ (buf, ".\n"))
  90                         break;
  91 @@ -2434,13 +2441,49 @@ do_ed_script (char const *inname, char c
  92             break;
  93         }
  94      }
  95 -    if (!pipefp)
  96 +    if (!tmpfp)
  97        return;
  98 -    if (fwrite ("w\nq\n", sizeof (char), (size_t) 4, pipefp) == 0
  99 -       || fflush (pipefp) != 0)
 100 +    if (fwrite ("w\nq\n", sizeof (char), (size_t) 4, tmpfp) == 0
 101 +       || fflush (tmpfp) != 0)
 102        write_fatal ();
 103 -    if (pclose (pipefp) != 0)
 104 -      fatal ("%s FAILED", editor_program);
 105 +
 106 +    if (lseek (tmpfd, 0, SEEK_SET) == -1)
 107 +      pfatal ("Can't rewind to the beginning of file %s", quotearg (tmpname));
 108 +
 109 +    if (! dry_run && ! skip_rest_of_patch) {
 110 +       int exclusive = *outname_needs_removal ? 0 : O_EXCL;
 111 +       *outname_needs_removal = true;
 112 +       if (inerrno != ENOENT)
 113 +         {
 114 +           *outname_needs_removal = true;
 115 +           copy_file (inname, outname, 0, exclusive, instat.st_mode, true);
 116 +         }
 117 +       sprintf (buf, "%s %s%s", editor_program,
 118 +                verbosity == VERBOSE ? "" : "- ",
 119 +                outname);
 120 +       fflush (stdout);
 121 +
 122 +       pid = fork();
 123 +       if (pid == -1)
 124 +         pfatal ("Can't fork");
 125 +       else if (pid == 0)
 126 +         {
 127 +           dup2 (tmpfd, 0);
 128 +           execl ("/bin/sh", "sh", "-c", buf, (char *) 0);
 129 +           _exit (2);
 130 +         }
 131 +       else
 132 +         {
 133 +           int wstatus;
 134 +           if (waitpid (pid, &wstatus, 0) == -1
 135 +               || ! WIFEXITED (wstatus)
 136 +               || WEXITSTATUS (wstatus) != 0)
 137 +             fatal ("%s FAILED", editor_program);
 138 +         }
 139 +    }
 140 +
 141 +    fclose (tmpfp);
 142 +    safe_unlink (tmpname);
 143
 144      if (ofp)
 145        {