patch 9.0.1833: [security] runtime file fixes

Problem:  runtime files may execute code in current dir
Solution: only execute, if not run from current directory

The perl, zig and ruby filetype plugins and the zip and gzip autoload
plugins may try to load malicious executable files from the current
working directory.  This is especially a problem on windows, where the
current directory is implicitly in your $PATH and windows may even run a
file with the extension `.bat` because of $PATHEXT.

So make sure that we are not trying to execute a file from the current
directory. If this would be the case, error out (for the zip and gzip)
plugins or silently do not run those commands (for the ftplugins).

This assumes, that only the current working directory is bad. For all
other directories, it is assumed that those directories were
intentionally set to the $PATH by the user.

Signed-off-by: Christian Brabandt <cb@256bit.org>

runtime/autoload/gzip.vim

@@ -10,12 +10,17 @@
 fun s:check(cmd)
   let name = substitute(a:cmd, '\(\S*\).*', '\1', '')
   if !exists("s:have_" . name)
+    " safety check, don't execute anything from the current directory
+    let f = fnamemodify(exepath(name), ":p:h") !=# getcwd()
+    if !f
+      echoerr "Warning: NOT executing " .. name .. " from current directory!"
+    endif
     let e = executable(name)
     if e < 0
       let r = system(name . " --version")
       let e = (r !~ "not found" && r != "")
     endif
-    exe "let s:have_" . name . "=" . e
+    exe "let s:have_" . name . "=" . (e && f)
   endif
   exe "return s:have_" . name
 endfun

runtime/autoload/zip.vim

@@ -57,6 +57,10 @@ if !exists("g:zip_extractcmd")
  let g:zip_extractcmd= g:zip_unzipcmd
 endif
 
+if fnamemodify(exepath(g:zip_unzipcmd), ":p:h") ==# getcwd()
+ echoerr "Warning: NOT executing " .. g:zip_unzipcmd .. " from current directory!"
+ finish
+endif
 " ----------------
 "  Functions: {{{1
 " ----------------

runtime/ftplugin/perl.vim

@@ -54,7 +54,8 @@ endif
 
 " Set this once, globally.
 if !exists("perlpath")
-    if executable("perl")
+    " safety check: don't execute perl from current directory
+    if executable("perl") && fnamemodify(exepath("perl"), ":p:h") != getcwd()
       try
 	if &shellxquote != '"'
 	    let perlpath = system('perl -e "print join(q/,/,@INC)"')

runtime/ftplugin/ruby.vim

@@ -99,41 +99,51 @@ function! s:build_path(path) abort
   return path
 endfunction
 
-if !exists('b:ruby_version') && !exists('g:ruby_path') && isdirectory(expand('%:p:h'))
-  let s:version_file = findfile('.ruby-version', '.;')
-  if !empty(s:version_file) && filereadable(s:version_file)
-    let b:ruby_version = get(readfile(s:version_file, '', 1), '')
-    if !has_key(g:ruby_version_paths, b:ruby_version)
-      let g:ruby_version_paths[b:ruby_version] = s:query_path(fnamemodify(s:version_file, ':p:h'))
-    endif
-  endif
+let s:execute_ruby = 1
+" Security Check, don't execute ruby from the current directory
+if fnamemodify(exepath("ruby"), ":p:h") ==# getcwd()
+  let s:execute_ruby = 0
 endif
 
-if exists("g:ruby_path")
-  let s:ruby_path = type(g:ruby_path) == type([]) ? join(g:ruby_path, ',') : g:ruby_path
-elseif has_key(g:ruby_version_paths, get(b:, 'ruby_version', ''))
-  let s:ruby_paths = g:ruby_version_paths[b:ruby_version]
-  let s:ruby_path = s:build_path(s:ruby_paths)
-else
-  if !exists('g:ruby_default_path')
-    if has("ruby") && has("win32")
-      ruby ::VIM::command( 'let g:ruby_default_path = split("%s",",")' % $:.join(%q{,}) )
-    elseif executable('ruby') && !empty($HOME)
-      let g:ruby_default_path = s:query_path($HOME)
-    else
-      let g:ruby_default_path = map(split($RUBYLIB,':'), 'v:val ==# "." ? "" : v:val')
+function SetRubyPath()
+  if !exists('b:ruby_version') && !exists('g:ruby_path') && isdirectory(expand('%:p:h'))
+    let s:version_file = findfile('.ruby-version', '.;')
+    if !empty(s:version_file) && filereadable(s:version_file) && s:execute_ruby
+      let b:ruby_version = get(readfile(s:version_file, '', 1), '')
+      if !has_key(g:ruby_version_paths, b:ruby_version)
+	let g:ruby_version_paths[b:ruby_version] = s:query_path(fnamemodify(s:version_file, ':p:h'))
+      endif
     endif
   endif
-  let s:ruby_paths = g:ruby_default_path
-  let s:ruby_path = s:build_path(s:ruby_paths)
-endif
 
-if stridx(&l:path, s:ruby_path) == -1
-  let &l:path = s:ruby_path
-endif
-if exists('s:ruby_paths') && stridx(&l:tags, join(map(copy(s:ruby_paths),'v:val."/tags"'),',')) == -1
-  let &l:tags = &tags . ',' . join(map(copy(s:ruby_paths),'v:val."/tags"'),',')
-endif
+  if exists("g:ruby_path")
+    let s:ruby_path = type(g:ruby_path) == type([]) ? join(g:ruby_path, ',') : g:ruby_path
+  elseif has_key(g:ruby_version_paths, get(b:, 'ruby_version', '')) && s:execute_ruby
+    let s:ruby_paths = g:ruby_version_paths[b:ruby_version]
+    let s:ruby_path = s:build_path(s:ruby_paths)
+  else
+    if !exists('g:ruby_default_path')
+      if has("ruby") && has("win32")
+	ruby ::VIM::command( 'let g:ruby_default_path = split("%s",",")' % $:.join(%q{,}) )
+      elseif executable('ruby') && !empty($HOME) && s:execute_ruby
+	let g:ruby_default_path = s:query_path($HOME)
+      else
+	let g:ruby_default_path = map(split($RUBYLIB,':'), 'v:val ==# "." ? "" : v:val')
+      endif
+    endif
+    let s:ruby_paths = g:ruby_default_path
+    let s:ruby_path = s:build_path(s:ruby_paths)
+  endif
+
+  if stridx(&l:path, s:ruby_path) == -1
+    let &l:path = s:ruby_path
+  endif
+  if exists('s:ruby_paths') && stridx(&l:tags, join(map(copy(s:ruby_paths),'v:val."/tags"'),',')) == -1
+    let &l:tags = &tags . ',' . join(map(copy(s:ruby_paths),'v:val."/tags"'),',')
+  endif
+endfunction
+
+call SetRubyPath()
 
 if (has("gui_win32") || has("gui_gtk")) && !exists("b:browsefilter")
   let b:browsefilter = "Ruby Source Files (*.rb)\t*.rb\n" .

runtime/ftplugin/zig.vim

@@ -39,7 +39,9 @@ endif
 
 let &l:define='\v(<fn>|<const>|<var>|^\s*\#\s*define)'
 
-if !exists('g:zig_std_dir') && exists('*json_decode') && executable('zig')
+" Safety check: don't execute zip from current directory
+if !exists('g:zig_std_dir') && exists('*json_decode') &&
+    \  executable('zig') && fnamemodify(exepath("zig"), ":p:h") != getcwd()
     silent let s:env = system('zig env')
     if v:shell_error == 0
         let g:zig_std_dir = json_decode(s:env)['std_dir']

src/version.c

@@ -699,6 +699,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1833,
 /**/
     1832,
 /**/