On Wed, Oct 28, 2026 at 12:14:29PM +0100, Matthieu Herrb wrote:
> On Wed, Oct 28, 2026 at 10:22:00AM +0100, Dirk-Wilhelm Peters wrote:
> > I have just found out by accident that xlock leaves its door slightly
> > ajar when using the marquee mode with a custom message:
> >
> > xlock -mode marquee -message "hack me"
> >
> > Simply type a few random characters to get back in.
> >
> > Abort trap
> >
> > This worked on several amd64 machines running 8.0 and 8.0-current.
> >
>
> This is a undefined behaviour of memcpy() on overlapping buffers. This
> patch should fix it.
I'm not a fan of memcpy aborting... I strongly suspect that everybody
else has a lenient memcpy (read: that behaves like memmove).
> None of the non default modes of xlock have been seriously audited for
> bugs like that. We still recommend to stick to -mode blank (the
> default).
At first I envisioned neutering -mode, but here's an even lazier diff.
>From a quick look I suspect that other modes are also affected but I'm
not volunteering to fix them, I only use -mode blank.
Thoughts?
Index: Makefile.bsd-wrapper
===================================================================
RCS file: /cvs/xenocara/app/xlockmore/Makefile.bsd-wrapper,v
diff -u -p -r1.15 Makefile.bsd-wrapper
--- Makefile.bsd-wrapper 26 Jun 2022 14:09:51 -0000 1.15
+++ Makefile.bsd-wrapper 28 Oct 2026 20:05:57 -0000
@@ -7,9 +7,9 @@ config.status:
AUTOCONF_VERSION="$(AUTOCONF_VERSION)" \
ACLOCAL="aclocal -I ${X11BASE}/share/aclocal" \
CC="${CC}" \
- CFLAGS="${CFLAGS}" \
+ CFLAGS="${CFLAGS} -Dmemcpy=memmove" \
CXX="${CXX}" \
- CXXFLAGS="${CXXFLAGS}" \
+ CXXFLAGS="${CXXFLAGS} -Dmemcpy=memmove" \
PKG_CONFIG_PATH="$(PKG_CONFIG_PATH)" \
CONFIG_SITE=$(CONFIG_SITE) \
sh ${.CURDIR}/configure --prefix=${X11BASE} \
--
jca
