bug#35429: 27.0.50; Arbitrary xdisp.c related crashes when working with overlay-using packages

[Eli Zaretskii]

> From: Kaushal Modi <kaushal.modi@gmail.com>
> Date: Fri, 26 Apr 2019 15:12:31 -0400
> Cc: 35429@debbugs.gnu.org
> 
> (gdb) p w->start
> $16 = XIL(0x89daa95)
> (gdb) xmarker
> $17 = (struct Lisp_Marker *) 0x89daa90
> (gdb) p $->buffer->name_
> $18 = XIL(0x7960234)
> (gdb) xstring
> $19 = (struct Lisp_String *) 0x7960230
> "standard-reading.org"
> (gdb)
> 
> That "standard-reading.org" is the Org file whose ~3000 character snippet 
> that I linked earlier.

So the window-start marker belongs to the wrong buffer.

Was standard-reading.org the buffer displayed in the selected window?
Did you switch buffers right before the crash?