tools/patch/patches/020-CVE-2018-1000156.patch

   1 From b3a0ca3deed00334f9feece43f76776b6a168e47 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  1 file changed, 66 insertions(+), 23 deletions(-)
  15
  16 --- a/src/pch.c
  17 +++ b/src/pch.c
  18 @@ -33,6 +33,7 @@
  19  # include <io.h>
  20  #endif
  21  #include <safe.h>
  22 +#include <sys/wait.h>
  23
  24  #define INITHUNKMAX 125                        /* initial dynamic allocation size */
  25
  26 @@ -2389,22 +2390,28 @@ do_ed_script (char const *inname, char c
  27      static char const editor_program[] = EDITOR_PROGRAM;
  28
  29      file_offset beginning_of_this_line;
  30 -    FILE *pipefp = 0;
  31      size_t chars_read;
  32 +    FILE *tmpfp = 0;
  33 +    char const *tmpname;
  34 +    int tmpfd;
  35 +    pid_t pid;
  36 +
  37 +    if (! dry_run && ! skip_rest_of_patch)
  38 +      {
  39 +       /* Write ed script to a temporary file.  This causes ed to abort on
  40 +          invalid commands such as when line numbers or ranges exceed the
  41 +          number of available lines.  When ed reads from a pipe, it rejects
  42 +          invalid commands and treats the next line as a new command, which
  43 +          can lead to arbitrary command execution.  */
  44 +
  45 +       tmpfd = make_tempfile (&tmpname, 'e', NULL, O_RDWR | O_BINARY, 0);
  46 +       if (tmpfd == -1)
  47 +         pfatal ("Can't create temporary file %s", quotearg (tmpname));
  48 +       tmpfp = fdopen (tmpfd, "w+b");
  49 +       if (! tmpfp)
  50 +         pfatal ("Can't open stream for file %s", quotearg (tmpname));
  51 +      }
  52
  53 -    if (! dry_run && ! skip_rest_of_patch) {
  54 -       int exclusive = *outname_needs_removal ? 0 : O_EXCL;
  55 -       assert (! inerrno);
  56 -       *outname_needs_removal = true;
  57 -       copy_file (inname, outname, 0, exclusive, instat.st_mode, true);
  58 -       sprintf (buf, "%s %s%s", editor_program,
  59 -                verbosity == VERBOSE ? "" : "- ",
  60 -                outname);
  61 -       fflush (stdout);
  62 -       pipefp = popen(buf, binary_transput ? "wb" : "w");
  63 -       if (!pipefp)
  64 -         pfatal ("Can't open pipe to %s", quotearg (buf));
  65 -    }
  66      for (;;) {
  67         char ed_command_letter;
  68         beginning_of_this_line = file_tell (pfp);
  69 @@ -2415,14 +2422,14 @@ do_ed_script (char const *inname, char c
  70         }
  71         ed_command_letter = get_ed_command_letter (buf);
  72         if (ed_command_letter) {
  73 -           if (pipefp)
  74 -               if (! fwrite (buf, sizeof *buf, chars_read, pipefp))
  75 +           if (tmpfp)
  76 +               if (! fwrite (buf, sizeof *buf, chars_read, tmpfp))
  77                     write_fatal ();
  78             if (ed_command_letter != 'd' && ed_command_letter != 's') {
  79                 p_pass_comments_through = true;
  80                 while ((chars_read = get_line ()) != 0) {
  81 -                   if (pipefp)
  82 -                       if (! fwrite (buf, sizeof *buf, chars_read, pipefp))
  83 +                   if (tmpfp)
  84 +                       if (! fwrite (buf, sizeof *buf, chars_read, tmpfp))
  85                             write_fatal ();
  86                     if (chars_read == 2  &&  strEQ (buf, ".\n"))
  87                         break;
  88 @@ -2435,13 +2442,49 @@ do_ed_script (char const *inname, char c
  89             break;
  90         }
  91      }
  92 -    if (!pipefp)
  93 +    if (!tmpfp)
  94        return;
  95 -    if (fwrite ("w\nq\n", sizeof (char), (size_t) 4, pipefp) == 0
  96 -       || fflush (pipefp) != 0)
  97 +    if (fwrite ("w\nq\n", sizeof (char), (size_t) 4, tmpfp) == 0
  98 +       || fflush (tmpfp) != 0)
  99        write_fatal ();
 100 -    if (pclose (pipefp) != 0)
 101 -      fatal ("%s FAILED", editor_program);
 102 +
 103 +    if (lseek (tmpfd, 0, SEEK_SET) == -1)
 104 +      pfatal ("Can't rewind to the beginning of file %s", quotearg (tmpname));
 105 +
 106 +    if (! dry_run && ! skip_rest_of_patch) {
 107 +       int exclusive = *outname_needs_removal ? 0 : O_EXCL;
 108 +       *outname_needs_removal = true;
 109 +       if (inerrno != ENOENT)
 110 +         {
 111 +           *outname_needs_removal = true;
 112 +           copy_file (inname, outname, 0, exclusive, instat.st_mode, true);
 113 +         }
 114 +       sprintf (buf, "%s %s%s", editor_program,
 115 +                verbosity == VERBOSE ? "" : "- ",
 116 +                outname);
 117 +       fflush (stdout);
 118 +
 119 +       pid = fork();
 120 +       if (pid == -1)
 121 +         pfatal ("Can't fork");
 122 +       else if (pid == 0)
 123 +         {
 124 +           dup2 (tmpfd, 0);
 125 +           execl ("/bin/sh", "sh", "-c", buf, (char *) 0);
 126 +           _exit (2);
 127 +         }
 128 +       else
 129 +         {
 130 +           int wstatus;
 131 +           if (waitpid (pid, &wstatus, 0) == -1
 132 +               || ! WIFEXITED (wstatus)
 133 +               || WEXITSTATUS (wstatus) != 0)
 134 +             fatal ("%s FAILED", editor_program);
 135 +         }
 136 +    }
 137 +
 138 +    fclose (tmpfp);
 139 +    safe_unlink (tmpname);
 140
 141      if (ofp)
 142        {