From 05f20a9790fa88011c1ce7099e0a660aa83195a9 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn=20Gustavsson?= <bjorn@erlang.org>
Date: Fri, 7 Apr 2017 13:07:48 +0200
Subject: erl_tar: Handle leading slashes and directory traversal attacks

---
 lib/stdlib/test/tar_SUITE.erl | 37 +++++++++++++++++++++++++++++++++++--
 1 file changed, 35 insertions(+), 2 deletions(-)

(limited to 'lib/stdlib/test/tar_SUITE.erl')

diff --git a/lib/stdlib/test/tar_SUITE.erl b/lib/stdlib/test/tar_SUITE.erl
index 2e1ae7bcff..76fa760fa8 100644
--- a/lib/stdlib/test/tar_SUITE.erl
+++ b/lib/stdlib/test/tar_SUITE.erl
@@ -27,7 +27,7 @@
 	 extract_from_binary_compressed/1, extract_filtered/1,
 	 extract_from_open_file/1, symlinks/1, open_add_close/1, cooked_compressed/1,
 	 memory/1,unicode/1,read_other_implementations/1,
-         sparse/1, init/1]).
+         sparse/1, init/1, leading_slash/1, dotdot/1]).
 
 -include_lib("common_test/include/ct.hrl").
 -include_lib("kernel/include/file.hrl").
@@ -41,7 +41,7 @@ all() ->
      extract_filtered,
      symlinks, open_add_close, cooked_compressed, memory, unicode,
      read_other_implementations,
-     sparse,init].
+     sparse,init,leading_slash,dotdot].
 
 groups() -> 
     [].
@@ -920,6 +920,39 @@ unicode_create_files() ->
 		   []
 	   end].
 
+leading_slash(Config) ->
+    PrivDir = proplists:get_value(priv_dir, Config),
+    Dir = filename:join(PrivDir, ?FUNCTION_NAME),
+    TarFile = filename:join(Dir, "leading_slash.tar"),
+    ok = filelib:ensure_dir(TarFile),
+    {ok,Fd} = erl_tar:open(TarFile, [write]),
+    TarMemberName = "e/d/c/b/a_member",
+    TarMemberNameAbs = "/" ++ TarMemberName,
+    Contents = <<"contents\n">>,
+    ok = erl_tar:add(Fd, Contents, TarMemberNameAbs, [verbose]),
+    ok = erl_tar:close(Fd),
+
+    ok = erl_tar:extract(TarFile, [{cwd,Dir}]),
+
+    {ok,Contents} = file:read_file(filename:join(Dir, TarMemberName)),
+    ok.
+
+dotdot(Config) ->
+    PrivDir = proplists:get_value(priv_dir, Config),
+    Dir = filename:join(PrivDir, ?FUNCTION_NAME),
+    ok = file:make_dir(Dir),
+    Tar = filename:join(Dir, "dotdot.tar"),
+    {ok,Fd} = erl_tar:open(Tar, [write]),
+    BeamFile = code:which(?MODULE),
+    ok = erl_tar:add(Fd, BeamFile, "a/./../../some_file", []),
+    ok = erl_tar:close(Fd),
+
+    {error,{_,unsafe_path=Error}} = erl_tar:extract(Tar, [{cwd,Dir}]),
+    false = filelib:is_regular(filename:join(PrivDir, "some_file")),
+    io:format("~s\n", [erl_tar:format_error(Error)]),
+
+    ok.
+
 %% Delete the given list of files.
 delete_files([]) -> ok;
 delete_files([Item|Rest]) ->
-- 
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