bug#27836: 26.0.50; Segfault in libotf when viewing article in gnus

[Eli Zaretskii]

> From: peder@klingenberg.no (Peder O. Klingenberg)
> Date: Wed, 26 Jul 2017 14:31:13 +0200
> 
> I received a horrendous mail last night from a cron job, 1.8M large and
> full of strange characters. Viewing it in gnus reproducibly crashes
> emacs for me.  The backtrace ends up somewhere in libotf, so possibly
> font-related.

Not font-related: related to shaping complex scripts.

First thing I'd suggest is make sure your libotf and related stuff
(m17n-db and libm17n-flt libraries) are the latest versions.  I'd even
suggest to install the latest development versions of them from their
respective repositories.

If that doesn't help, please try to extract the minimal part of the
file that still reproduces the crash.  Judging by the backtrace, the
problem happens around byte 1341327 into the file, so start by taking
a small portion around that place, and enlarge it in both directions
as needed until it starts crashing.