Currently, slock only clears the entered passwd buffer as part of
auth_userokay(3). If the user aborts the password entry with ESC or
clears the entered password with multiple backspaces, a cleartext
copy of the entered password is kept in memory. Use explicit_bzero()
to avoid this.
While there, add __dead and printf attributes to the die() function.
I've been running with this patch for quite a while (> 3 months) with no
issues on amd64 and macppc.
The port runs just fine, but when I compile it, I get the following
warning which I don't know how to fix properly:
CFLAGS = -O2 -pipe -std=c99 -pedantic -Wall -I/usr/X11R6/include
-DVERSION="1.3" -DHAVE_BSD_AUTH
LDFLAGS = -L/usr/X11R6/lib -lX11 -lXext -lXrandr
CC = cc
creating config.h from config.def.h
cc -c -O2 -pipe -std=c99 -pedantic -Wall -I/usr/X11R6/include
-DVERSION=\"1.3\" -DHAVE_BSD_AUTH slock.c
In file included from /usr/X11R6/include/X11/Xlib.h:47,
from /usr/X11R6/include/X11/extensions/Xrender.h:28,
from /usr/X11R6/include/X11/extensions/Xrandr.h:33,
from slock.c:16:
/usr/X11R6/include/X11/Xfuncproto.h:159:24: warning: ISO C does not permit
named variadic macros
slock.c: In function 'readpw':
slock.c:175: warning: implicit declaration of function 'explicit_bzero'
Could someone help me with fixing that, please?
Index: Makefile
===================================================================
RCS file: /cvs/ports/x11/slock/Makefile,v
retrieving revision 1.14
diff -u -p -r1.14 Makefile
--- Makefile 6 Jul 2016 21:34:15 -0000 1.14
+++ Makefile 30 Jul 2016 15:55:05 -0000
@@ -3,7 +3,7 @@
COMMENT= simple X screen locker
DISTNAME= slock-1.3
-REVISION= 0
+REVISION= 1
CATEGORIES= x11
Index: patches/patch-slock_c
===================================================================
RCS file: patches/patch-slock_c
diff -N patches/patch-slock_c
--- /dev/null 1 Jan 1970 00:00:00 -0000
+++ patches/patch-slock_c 30 Jul 2016 15:55:05 -0000
@@ -0,0 +1,33 @@
+$OpenBSD$
+--- slock.c.orig Fri Feb 12 20:29:02 2016
++++ slock.c Sat Jul 30 17:54:15 2016
+@@ -47,7 +47,7 @@ static Bool rr;
+ static int rrevbase;
+ static int rrerrbase;
+
+-static void
++static void __attribute__((__noreturn__, __format__(printf, 1, 2)))
+ die(const char *errstr, ...)
+ {
+ va_list ap;
+@@ -172,10 +172,12 @@ readpw(Display *dpy, const char *pws)
+ break;
+ case XK_Escape:
+ len = 0;
++ explicit_bzero(passwd, sizeof(passwd));
+ break;
+ case XK_BackSpace:
+ if (len)
+ --len;
++ explicit_bzero(passwd + len, 1);
+ break;
+ default:
+ if (num && !iscntrl((int)buf[0]) && (len + num
< sizeof(passwd))) {
+@@ -185,6 +187,7 @@ readpw(Display *dpy, const char *pws)
+ break;
+ }
+ color = len ? INPUT : (failure || failonclear ? FAILED
: INIT);
++ explicit_bzero(buf, sizeof(buf));
+ if (running && oldc != color) {
+ for (screen = 0; screen < nscreens; screen++) {
+ XSetWindowBackground(dpy,
locks[screen]->win, locks[screen]->colors[color]);
