Re: [bug-patch] [PATCH] do not let a malicious patch create files above current directory

[Bert Wesarg]

On Tue, Feb 1, 2011 at 11:31, Jim Meyering <address@hidden> wrote:
> Surprised that no one has posted a patch for this yet, I wrote my own:
>
> From aeed44154b388210f0e70dbe802a78949224aa97 Mon Sep 17 00:00:00 2001
> From: Jim Meyering <address@hidden>
> Date: Tue, 1 Feb 2011 11:21:15 +0100
> Subject: [PATCH] do not let a malicious patch create files above current 
> directory
>
> This addresses CVE-2010-4651, reported by Jakub Wilk.
> https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2010-4651
> * src/pch.c (intuit_diff_type): Reject any file name containing a
> component of "..".
> * tests/dot-dot: New file.  Test for this.
> * tests/Makefile.am (TESTS): Add it.
>
> 2002, 2009, 2010, 2011 Free Software Foundation, Inc.
> ---
>  ChangeLog         |   12 +++++++++++-
>  src/pch.c         |   14 +++++++++++++-
>  tests/Makefile.am |    3 ++-
>  tests/dot-dot     |   45 +++++++++++++++++++++++++++++++++++++++++++++
>  4 files changed, 71 insertions(+), 3 deletions(-)
>  create mode 100644 tests/dot-dot
>
> diff --git a/ChangeLog b/ChangeLog
> index bbe5fe7..88db61c 100644
> --- a/ChangeLog
> +++ b/ChangeLog
> @@ -1,3 +1,13 @@
> +2011-02-01  Jim Meyering  <address@hidden>
> +
> +       do not let a malicious patch create files above current directory
> +       This addresses CVE-2010-4651, reported by Jakub Wilk.
> +       https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2010-4651
> +       * src/pch.c (intuit_diff_type): Reject any file name containing a
> +       component of "..".
> +       * tests/dot-dot: New file.  Test for this.
> +       * tests/Makefile.am (TESTS): Add it.
> +
>  2010-12-04  Andreas Gruenbacher <address@hidden>
>
>        * src/util.c (make_tempfile): Create missing directories when
> @@ -3594,7 +3604,7 @@ Sun Dec 17 17:29:48 1989  Jim Kingdon  (kingdon at 
> hobbes.ai.mit.edu)
>  Copyright (C) 1984, 1985, 1986, 1987, 1988 Larry Wall.
>
>  Copyright (C) 1989, 1990, 1991, 1992, 1993, 1997, 1998, 1999, 2000, 2001,
> -2002, 2009, 2010 Free Software Foundation, Inc.
> +2002, 2009, 2010, 2011 Free Software Foundation, Inc.
>
>  This file is part of GNU Patch.
>
> diff --git a/src/pch.c b/src/pch.c
> index 1653ee4..54a9acc 100644
> --- a/src/pch.c
> +++ b/src/pch.c
> @@ -3,7 +3,7 @@
>  /* Copyright (C) 1986, 1987, 1988 Larry Wall
>
>    Copyright (C) 1990, 1991, 1992, 1993, 1997, 1998, 1999, 2000, 2001,
> -   2002, 2003, 2006, 2009, 2010 Free Software Foundation, Inc.
> +   2002, 2003, 2006, 2009, 2010, 2011 Free Software Foundation, Inc.
>
>    This program is free software: you can redistribute it and/or modify
>    it under the terms of the GNU General Public License as published by
> @@ -935,6 +935,18 @@ intuit_diff_type (bool need_header, mode_t *p_file_type)
>        instat = st[i];
>       }
>
> +    if (inname)
> +      {
> +       /* If inname starts with "../" ends with "/.." or contains
> +          "/../", then issue a fatal error.  */
> +       size_t len = strlen (inname);
> +       if (strnEQ (inname, "../", 3)
> +           || strnEQ (inname + len - 3, "/..", 3)

I miss a check, that len is at least 3.

Bert