GNU bug report logs - #34469
26.1; EWW stops renderring web page on null byte

Previous Next

Full log

View this message in rfc822 format

From: Eli Zaretskii <eliz <at> gnu.org>
To: Robert Pluim <rpluim <at> gmail.com>
Cc: rgm <at> gnu.org, 34469 <at> debbugs.gnu.org, nicholasdrozd <at> gmail.com
Subject: bug#34469: 26.1; EWW stops renderring web page on null byte
Date: Tue, 19 Feb 2019 18:30:48 +0200

> From: Robert Pluim <rpluim <at> gmail.com>
> Date: Tue, 19 Feb 2019 11:06:37 +0100
> Cc: 34469 <at> debbugs.gnu.org, Nicholas Drozd <nicholasdrozd <at> gmail.com>
> 
> Glenn Morris <rgm <at> gnu.org> writes:
> 
> > Perhaps eww-display-html should replace null bytes (with whatever the
> > html standard says is appropriate) before calling
> > libxml-parse-html-region. It already replaces CRLF.
> 
> Chrome at least just strips the null byte completely.
> 
> There is apparently a class of attacks that uses the null character
> for nefarious purposes, so how about something like this:
> 
> diff --git a/lisp/net/eww.el b/lisp/net/eww.el
> index 1cc4557ce1..9b57bc43e4 100644
> --- a/lisp/net/eww.el
> +++ b/lisp/net/eww.el
> @@ -448,8 +448,8 @@ eww-display-html
>  		    (decode-coding-region (point) (point-max) encode)
>  		  (coding-system-error nil))
>                  (save-excursion
> -                  ;; Remove CRLF before parsing.
> -                  (while (re-search-forward "\r$" nil t)
> +                  ;; Remove CRLF and NULL before parsing.
> +                  (while (re-search-forward "\r$\\|\000" nil t)
>                      (replace-match "" t t)))

It is un-Emacsy, IMO, to remove content without a trace.  (CR is
different: we simply convert text to Unix LF-only EOL format.)  So I'd
suggest to replace with "^@" or "\000" or "NUL" or something to that
effect.  Even U+FFFD would be better than removing.

(We could get fancy and have a defcustom for those who do want the
null bytes removed.)

Thanks.

Previous Next

GNU bug tracking system
Copyright (C) 1999 Darren O. Benham, 1997,2003 nCipher Corporation Ltd, 1994-97 Ian Jackson.