bug#60295: [PATCH] Fix htmlfontify.el command injection vulnerability

[Eli Zaretskii <eliz@gnu.org>]

> Date: Sat, 24 Dec 2022 17:03:09 +0800
> From: lux <lx@shellcodes.org>
> 
> Test information:
> Emacs version: GNU Emacs 29.0.60
> OS: Fedora Linux 37
> 
> htmlfontify.el has a command injection vulnerability:
> 
> (defcustom hfy-istext-command "file %s | sed -e 's@^[^:]*:[ \t]*@@'"
>   :tag   "istext-command"
>   :type  '(string))
> 
> (defun hfy-text-p (srcdir file)
>   (let* ((cmd (format hfy-istext-command (expand-file-name file
> srcdir))) (rsp (shell-command-to-string    cmd)))
>     ...))
> 
> Parameter 'file' and parameter 'srcdir' come from external input, and 
> parameters are not escape. So, if file name or directory name contains
> shell characters and will be executed.
> 
> For example:
> 
> $ mkdir vul_test
> $ cd vul_test
> $ echo hello > ";uname>hack.txt#"
> $ ls
> ;uname>hack.txt#
> 
> In Emacs, type M-x htmlfontify-copy-and-link-dir, and inputing vul_test
> path, at this time, hack.txt is added to the vul_test directory:
> 
> $ ls
> ;uname>hack.txt#  hack.txt#
> $ cat hack.txt\#
> Linux
> 
> The attachment is the patch file, thanks.

Thanks, installed on the emacs-29 branch, and closing the bug.