[tex-k] segfault in texlive2020 pdftex/luatex/xetex/ptex/...

[David Carlisle]

with the cygwin build of texlive 2020 I get a segfault from this plain tex
document

%%%

\def\z{\number\z}\z

\end

%%%


you can replace \number by \the or \if or any other  primitive that forces
expansion.

on linux and windows by default it doesn't segfault and gives the expected
expansion depth error

% cygwin
$ tex segv
This is TeX, Version 3.14159265 (TeX Live 2020) (preloaded format=tex)
(./segv.texSegmentation fault (core dumped)


% ubuntu/wsl
$tex segv
This is TeX, Version 3.14159265 (TeX Live 2020) (preloaded format=tex)
(./segv.tex
! TeX capacity exceeded, sorry [expansion depth=10000].
\z ->\number
             \z
l.1 \def\z{\number\z}\z

No pages of output.
Transcript written on segv.log.

But increasing the depth limit on the (wsl ubuntu) version it again dumps
core

$ tex --cnf-line="expand_depth=200000" segv
This is TeX, Version 3.14159265 (TeX Live 2020) (preloaded format=tex)
(./segv.texSegmentation fault (core dumped)


Hironobu Yamashita confirms you can get this in the mac if you increase the
expansion depth


SEGV Confirmed here (macOS), with $ pdftex
-cnf-line="expand_depth=20000000" test.tex


on cygwin, this works

tex --cnf-line="expand_depth=5382" segv

but 5383 segfaults

so it seems that the issue isn't specific to cygwin other than it kicks in
sooner with the default values,

David
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