GNU bug report logs - #10536
23.3; Make base64-decode more fault tolerant

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Package: emacs;

Reported by: Wolfram Gloger <wmglo <at> dent.med.uni-muenchen.de>

Date: Tue, 17 Jan 2012 17:09:02 UTC

Severity: minor

Tags: patch, wontfix

Found in version 23.3

Done: Lars Ingebrigtsen <larsi <at> gnus.org>

Bug is archived. No further changes may be made.

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From: Eli Zaretskii <eliz <at> gnu.org>
To: Lars Ingebrigtsen <larsi <at> gnus.org>
Cc: 10536 <at> debbugs.gnu.org, wmglo <at> dent.med.uni-muenchen.de
Subject: bug#10536: 23.3; Make base64-decode more fault tolerant
Date: Wed, 18 Apr 2018 09:20:43 +0300

> From: Lars Ingebrigtsen <larsi <at> gnus.org>
> Date: Wed, 18 Apr 2018 00:22:42 +0200
> Cc: 10536 <at> debbugs.gnu.org
> 
> > --- src/fns.c~	2011-04-05 05:46:44.000000000 +0200
> > +++ src/fns.c	2012-01-17 13:59:26.000000000 +0100
> > @@ -3590,7 +3590,8 @@
> >
> >        if (c == '=')
> >  	{
> > -	  READ_QUADRUPLET_BYTE (-1);
> > +	  /* Be tolerant against missing final padding '='.  */
> > +	  READ_QUADRUPLET_BYTE (e-to);
> 
> It probably won't harm anything to add this patch...  On the other hand,
> it's not very common to have base64 encoded data that fails in this
> manner.
> 
> What do the rest of you people think?  (I think I'm slightly for
> applying the patch.  "Be liberal in what you receive" and all that.)

Could this "omission" be a sign of malicious stuff in there?  If so,
maybe it's better to introduce a variable that would allow this to be
tolerated, and by default fail with a message telling the user that if
they trust the source of the data, set the variable and retry?
This bug report was last modified 6 years and 22 days ago.

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