bug#42943: 28.0.50; Emacsclient crashes in ftcrfont_glyph_extents

[Eli Zaretskii]

> From: "Basil L. Contovounesios" <contovob@tcd.ie>
> Date: Thu, 20 Aug 2020 01:47:32 +0100
> 
> --8<---------------cut here---------------start------------->8---
> glyph 7 row 0 col 7 nrows 1 m 0x5555561a7660 r 0x555556495210 c 0x555556495256
> 
> glyph 7 row 0 col 7 nrows 1 m 0x5555561a7660 r 0x555556495210 c 0x555556495256
> 
> glyph 63 row 0 col 63 nrows 1 m 0x5555561a7660 r 0x555556495210 c 
> 0x555556495486
> sz 24 len 1 from 0 i 0
> glyph 3 row 0 col 3 nrows 1 m 0x5555561a7660 r 0x555556495210 c 0x55555649522e
> sz 24 len 1 from 0 i 0
> glyph 1135 row 8 col 111 nrows 10 m 0x5555562304d0 r 0x2073756c50656d55 c 
> 0x2073756c506571ab
> --8<---------------cut here---------------end--------------->8---

Is 0x2073756c506571ab a bogus pointer, i.e. it cannot be dereferenced?
If so, you need to figure out where did it come from.  It could have
come from the xmalloc call, but then why the trace around that call
are not shown in your printfs?

And what is sizeof(struct font_metrics) there?  I see no printfs which
show that, so I can only guess.