fix CVE-2016-6866

diff --git a/slock.c b/slock.c
index 847b328..8ed59ca 100644 (file)
--- a/slock.c
+++ b/slock.c
@@ -123,7 +123,7 @@ readpw(Display *dpy)
 readpw(Display *dpy, const char *pws)
 #endif
 {
-       char buf[32], passwd[256];
+       char buf[32], passwd[256], *encrypted;
        int num, screen;
        unsigned int len, color;
        KeySym ksym;
@@ -159,7 +159,11 @@ readpw(Display *dpy, const char *pws)
 #ifdef HAVE_BSD_AUTH
                                running = !auth_userokay(getlogin(), NULL, "auth-slock", passwd);
 #else
-                               running = !!strcmp(crypt(passwd, pws), pws);
+                               errno = 0;
+                               if (!(encrypted = crypt(passwd, pws)))
+                                       fprintf(stderr, "slock: crypt: %s\n", strerror(errno));
+                               else
+                                       running = !!strcmp(encrypted, pws);
 #endif
                                if (running) {
                                        XBell(dpy, 100);
@@ -312,6 +316,8 @@ main(int argc, char **argv) {
 
 #ifndef HAVE_BSD_AUTH
        pws = getpw();
+       if (strlen(pws) < 2)
+               die("slock: failed to get user password hash.\n");
 #endif
 
        if (!(dpy = XOpenDisplay(NULL)))