GNU bug report logs - #35814
27.0.50; Broken font display

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From: Alex Gramiak <agrambot <at> gmail.com>
To: Andy Moreton <andrewjmoreton <at> gmail.com>
Cc: Katsumi Yamaoka <yamaoka <at> jpl.org>, 35814 <at> debbugs.gnu.org, Juri Linkov <juri <at> linkov.net>
Subject: bug#35814: 27.0.50; Broken font display
Date: Tue, 21 May 2019 15:19:29 -0600

Andy Moreton <andrewjmoreton <at> gmail.com> writes:

> Alex, at the end of xfont_draw() in xfont.c, we now have:
>
>       else
>         {
>           const unsigned code = s->char2b[from];
>           const XChar2b char2b = { .byte1 = code >> 8,
>                                    .byte2 = code & 0xFF };
>           XDrawImageString16 (display, FRAME_X_DRAWABLE (s->f),
>                               gc, x, y, &char2b, len);
>         }
>
> and:
>       else
>         {
>           const unsigned code = s->char2b[from];
>           const XChar2b char2b = { .byte1 = code >> 8,
>                                    .byte2 = code & 0xFF };
>           XDrawString16 (display, FRAME_X_DRAWABLE (s->f),
>                          gc, x, y, &char2b, len);
>         }
>
> Both of these pass "len", but use a single XChar2b on the stack, so
> this causes an overrun (and draws random stack contents).

Wow, sorry, that was a bad mistake. I've applied commit 5a024b72c to
master; can those who experience the bug affirm that it's been fixed?

It appears that I only tested with fonts that make s->padding_p true,
and I can't seem to find a font on my system that doesn't.

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