On Fri, Feb 18, 2022 at 03:12:14PM +0100, Rhonda D'Vine wrote:
> Dear Lee,
>
> * Lee Garrett <deb...@rocketjump.eu> [2022-02-09 18:27:38 CET]:
> > Package: tetradraw
> > Version: 2.0.3-9+b2
> > Followup-For: Bug #716386
> > X-Debbugs-Cc: deb...@rocketjump.eu
> >
> > Hi Rhonda,
> >
> > sorry to grave dig this bug report, but it seems that tetradraw might be
> > broken
> > for a couple of releases now. On bullseye it segfaults with rc 139. A few
> > people
> > in #debian reported the same issue, so it looks like it's 100% reproducible.
> > Since I'd love to make some nice ascii art for my /etc/motd, it would be
> > nice if
> > you could find the time to fix it. Thanks in advance!
>
> You are definitely right on that. I think in one of the bugs there is
> a workaround for the issue: It runs smoothly on a virtual console
> instead of within a terminal in Xorg. So if that's possible, I suggest
> to go that path.
>
> What also works is starting it with TERM=linux. This gives a hint in
> what area the issue may lie. I am unfortunately not a well enough coder
> to dig further into it, but those are the workarounds that I am aware
> of, and might give people a hint on where to look into for fixing this.
I was looking at this and the segfault is from src/term.c, line 205.
The part of the code is:
for(count = 1; count < COLOR_PAIRS; count++) {
init_pair(count, count % COLORS, count / COLORS);
colours[count % COLORS][count / COLORS] = count;
}
Further debugging showed COLOR_PAIRS was 65536, so the value of count can be
65535, and COLORS is defined as 256. So, colours[count % COLORS][count / COLORS]
can become colours[65535 % 256][65535 / 256] which means the max array location
it can try to access of colours[0][255]. But colours is declared as
colours[8][8],
so its trying to access memory locations beyond what has been allocated to it.
The following patch will stop the segfault but I dont know what tetradraw is
supposed
to do to check if it has other impact or not.
--- tetradraw-2.0.3.orig/src/global.h
+++ tetradraw-2.0.3/src/global.h
@@ -5,7 +5,7 @@
extern coordinate td_maxx;
extern coordinate td_maxy;
-extern colour colours[COLOURS][COLOURS];
+extern colour colours[256][256];
extern int remote;
extern int pagecnt;
extern char default_highascii[20][10];
--- tetradraw-2.0.3.orig/src/tetradraw.c
+++ tetradraw-2.0.3/src/tetradraw.c
@@ -45,7 +45,7 @@ void load_options();
coordinate td_maxx = 0;
coordinate td_maxy = 0;
-colour colours[COLOURS][COLOURS];
+colour colours[256][256];
canvas *pages[9] = {
NULL,
NULL,
--- tetradraw-2.0.3.orig/src/tetraview.c
+++ tetradraw-2.0.3/src/tetraview.c
@@ -41,7 +41,7 @@
coordinate td_maxx = 0;
coordinate td_maxy = 0;
-colour colours[COLOURS][COLOURS];
+colour colours[256][256];
int remote = 0;
--
Regards
Sudip
